The Essential Grammar Guide: Mastering the Japanese Indirect Question Structure(疑問詞 + 〜か) for the JLPT

疑問詞 + 〜か

If you’re gearing up for the JLPT, whether you are aiming for N3, N2, or even N1, you know that the journey into advanced Japanese requires mastering complex sentence structures. Simple sentence patterns that you learned early on are slowly replaced by intricate clauses and embedded phrases. This is where many learners hit a wall, especially when dealing with concepts that don’t have a direct equivalent in their native tongue.

JLPT N4 Complete Guide is available in this article before you dive into the grammar details.

Today, we are diving deep into a structure that is absolutely fundamental for expressing complex thoughts and conveying information naturally: the indirect question using the pattern [Question Word] + Verb/Noun/Adjective + か. This seemingly small particle 「か」 takes on a new, powerful role here, transforming a simple question into a core component of a larger sentence.

We understand your frustration. You might know what a question word like doko (どこ) means, and you know that ka (か) usually marks a question. But putting them together in the middle of a sentence—like in 「彼はどこに行ったか知っていますか」 (Do you know where he went?)—can feel confusing. Don’t worry. This guide will break down this essential grammar point, clarify its rules, and show you exactly how the JLPT tests your knowledge of it.

The Power Shift: Understanding Indirect Questions

The structure [疑問詞]〜か is used to embed a specific piece of unknown information (an entire question) into a larger statement or another question. In English, this is known as an indirect question (or embedded question).

Think about the difference between these two English sentences:

1. “What time is it?” (Direct Question)
2. “I need to check what time it is.” (Indirect Question)

In Japanese, the particle 「か」 plays the role of turning the entire embedded clause into a nominal phrase (a noun phrase) that can act as the object or subject of the main verb.

The Function of 「か」 in the Middle of a Sentence

When 「か」 is used at the end of a simple sentence (e.g., 寿司を食べますか?), it dictates the sentence’s function as a question.

However, when following a question word and a plain-form verb mid-sentence, the function of 「か」 is to contain the unknown element. It signals that the information contained within that clause is the subject of the main verb (e.g., knowing, deciding, telling, investigating).

The structure allows you to use sophisticated verbs of reporting, knowing, or thinking (like 知る, 教える, 考える, 決める) and make the unknown information the direct content that those actions revolve around.

The Fundamental Rules of [疑問詞]〜か Grammar

To use this structure correctly and confidently on the JLPT, you must internalize two critical rules:

Rule 1: Always Use the Plain Form (Ordinary Form)

This is arguably the most common mistake made by intermediate learners. When forming an indirect question clause, the verb, noun, or adjective immediately preceding 「か」 must be in the plain form (also known as the casual or dictionary form), regardless of how polite the main sentence is.

The entire clause (Question Word + Plain Form + か) is being treated as a nominal element (a noun), which means it requires the plain form conjugation within the clause itself.

Plain Form Examples:

• Present Tense Verb: いつ始めるか (When we will start)
• Past Tense Verb: 誰がやったか (Who did it)
• I-Adjective: どれぐらい高いか (How expensive it is)
• Na-Adjective: なぜそれが必要か (Why it is necessary)
• Noun: 誰がリーダーか (Who the leader is)

Crucial Note on Nouns and Na-Adjectives: Unlike forming a plain statement where you would use 「だ」 (e.g., 彼は学生だ), you generally drop the copula 「だ」 immediately before 「か」 in this specific indirect question structure. The one exception is the past tense, which still uses だった.

• ❌ (Incorrect) 山田さんは誰だか知っていますか。
• ✅ (Correct) 山田さんが誰か知っていますか？ (Do you know who Yamada-san is?)

Rule 2: Integrating the Clause into the Main Sentence

The entire bracketed clause containing the indirect question functions as the object or subject of the main clause. The structure is fixed:

[Main Subject] は/が + [QW + V-plain + か] (Object/Subject) + [Main Verb]

The indirect question clause itself often takes the role of the object, particularly with verbs like shiru (知る), kangaeru (考える), and kimeru (決める). While the object particle を (o) is technically required for the entire noun phrase, it is often omitted in natural speech and less formal writing, though it may appear in formal documents or longer, more complex sentences.

• With Object Particle (Formal/Clear): 誰が行くかを教えてください。 (Please tell me who is going.)
• Without Object Particle (Common): 誰が行くか教えてください。 (Please tell me who is going.)

Whether the particle is present or absent, you must recognize that the entire block ending in 「か」 is the information the main verb is acting upon.

Essential Verb Combinations for JLPT Success

On the JLPT, this structure is tested heavily in combination with specific types of main verbs. Understanding these groupings will significantly improve your comprehension and production skills.

Category A: Verbs of Knowing and Certainty

These verbs confirm whether the information in the embedded question is known or understood.

• 知る (しる / to know): The most common verb used. (例: 彼はどこに住んでいるか知っていますか？ / Do you know where he lives?)
• わかる (to understand / to become clear): Focuses on comprehension or resolution of the unknown. (例: この問題の答えがどうなるかわかりません。 / I don’t know what the answer to this problem will be.)
• 確認する (かくにんする / to confirm): Used when checking the accuracy of the unknown fact. (例: 予約時間に間違いがないか確認した。 / I confirmed whether the reservation time was correct.)

Category B: Verbs of Communication and Inquiry

These verbs involve relaying or seeking the unknown information.

• 教える (おしえる / to tell, to inform): The information is being transmitted. (例: それがどういう意味か、私に教えてください。 / Please tell me what that means.)
• 聞く (きく / to ask): Often used to ask for the information, although it can sometimes use 〜かどうか. (例: 先生に次の試験はいつか聞きました。 / I asked the teacher when the next exam is.)
• 伝える (つたえる / to convey): Used for passing information from one party to another. (例: 彼に明日何を持ってくるか伝えた。 / I told him what to bring tomorrow.)

Category C: Verbs of Decision and Consideration

These verbs involve a process of thought or a conclusion based on the unknown factors.

• 決める (きめる / to decide): The unknown element is the factor being decided upon. (例: どちらの案を採用するか、まだ決めていません。 / I haven’t decided which plan to adopt yet.)
• 考える (かんがえる / to think): The unknown element is the subject of the mental process. (例: 彼女はなぜ辞職したか考えている。 / She is thinking about why she resigned.)
• 検討する (けんとうする / to consider): A more formal term for thinking deeply about the options. (例: 費用がどれぐらいかかるかを検討する必要がある。 / We need to consider how much the cost will be.)

Detailed Examples for Everyday Use and JLPT Context

Let’s solidify the structure with three comprehensive examples covering different parts of speech, illustrating how complex thoughts are streamlined using 疑問詞〜か.

Example 1: Inquiring about a Time (Verb)

This situation is common in professional and academic settings where scheduling is key. It demonstrates the use of a simple past tense verb within the indirect question.

日本語: 彼女がいつ出発したか、ご存知ですか。

Romaji: Kanojo ga itsu shuppatsu shita ka, gozonji desu ka.

English Translation: Do you know when she departed?

Breakdown:

• 疑問詞: いつ (itsu / when)
• Plain Form Verb (Past): 出発した (shuppatsu shita / departed)
• Indirect Question Clause: 彼女がいつ出発したか (When she departed)
• Main Verb: ご存知ですか (Do you know? – Polite form of 知る)

Key Takeaway: The sentence asks for knowledge about a specific past event. Note how the formality is carried by the main verb (ご存知ですか) even though the embedded clause uses the casual past tense (した).

Example 2: Determining an Option (Noun/Na-Adjective)

This is frequently used in decision-making and project management, common subjects in JLPT reading passages.

日本語: 今の状況で、誰が一番適任か、会議で決めましょう。

Romaji: Ima no jōkyō de, dare ga ichiban tekinin ka, kaigi de kimemashō.

English Translation: Let’s decide in the meeting who is the most suitable person for the current situation.

Breakdown:

• 疑問詞: 誰 (dare / who)
• Plain Form Noun/Na-Adjective: 一番適任 (ichiban tekinin / most suitable person). Note the omission of だ before か.
• Indirect Question Clause: 誰が一番適任か (Who is the most suitable person)
• Main Verb: 決めましょう (kimemashō / Let’s decide)

Key Takeaway: The object of the decision-making verb 決める is the result of the question: Who is the most suitable?

Example 3: Measuring a Degree (I-Adjective)

Used for conveying subjective measurements or degrees, often found in essays or opinion pieces.

日本語: 私は、その政策がどれぐらい効果的か評価している。

Romaji: Watashi wa, sono seisaku ga dore gurai kōkateki ka hyōka shite iru.

English Translation: I am evaluating how effective that policy is.

Breakdown:

• 疑問詞/Phrase: どれぐらい (dore gurai / to what degree/how much)
• Plain Form Na-Adjective: 効果的 (kōkateki / effective). Again, drop だ.
• Indirect Question Clause: その政策がどれぐらい効果的か (How effective that policy is)
• Main Verb: 評価している (hyōka shite iru / I am evaluating)

Key Takeaway: The entire indirect question clause serves as the object of the verb 評価する (to evaluate). The goal of the evaluation is to determine the degree of effectiveness.

Advanced Pitfalls and Nuances for High JLPT Scores

To move past intermediate proficiency, you must distinguish this core structure from similar-sounding grammatical forms.

Pitfall A: Confusing 「疑問詞〜か」 with 「疑問詞〜のか」

As you progress to N2 and N1, you will inevitably encounter the structure using the nominalizer の (no), often contracted to ん (n), immediately before か.

• [疑問詞] + V-plain + か: The neutral, standard indirect question. It simply reports the content of the question.
• [疑問詞] + V-plain + のか: This version adds an explanatory or emphatic nuance. It is often used when the speaker is seeking or considering the *reason* or *explanation* behind the unknown fact. It implies a deeper query.

Example Comparison:

1. 彼はどこに住んでいるか知りたい。 (I want to know where he lives. – Neutral request for information.)

2. 彼はどこに住んでいるのか知りたい。 (I want to know the answer/explanation as to where he lives. – Slightly more emphasis, often implying a context or reason why this information is relevant.)

For most JLPT grammar questions focusing on the standard indirect question, the neutral 「か」 is the correct choice unless the context explicitly demands an explanatory nuance.

Pitfall B: The Distinction Between 「疑問詞〜か」 and 「〜かどうか」

This is a critical distinction that frequently appears on the JLPT:

• Use [疑問詞]〜か when the original question seeks specific information (who, what, where, when, why, how).
• Use [V-plain] + かどうか (ka dou ka) when the original question was a simple Yes/No question.

Yes/No Question Example:

Direct Question: 明日雨が降るか？ (Will it rain tomorrow?)

Indirect Form: 明日雨が降るかどうか、調べてください。 (Please check whether or not it will rain tomorrow.)

If you mistakenly use only 「か」 for a Yes/No question in formal writing (e.g., 雨が降るか調べてください), while sometimes acceptable conversationally, it is less precise and less common than the full 「かどうか」 structure, which explicitly includes the possibility of the negative outcome (どうか = or not).

Pitfall C: Maintaining Subject and Topic Clarity

In complex Japanese sentences, keeping track of who is doing what (the subject) and what the topic is (marked by は) is difficult. In the indirect question structure, you often have a subject inside the embedded clause (marked by が) and a separate subject/topic for the main sentence.

Example:

私は、[彼がなぜ怒ったか]を知らない。

The main subject is 私 (I), and the subject of the embedded clause (the reason for the anger) is 彼 (he). Make sure you use the appropriate particle (usually が) within the embedded clause to denote the actor of the plain-form verb.

JLPT Practice Strategy: Integrating [疑問詞]〜か

This grammar point is tested not only in dedicated grammar sections but heavily in the listening and reading parts of the JLPT.

1. Grammar Checks (文法問題)

Focus on testing your ability to choose the correct conjugation before 「か」. If you see a multiple-choice question testing this structure, immediately eliminate options that use the polite form (ます/です) or options that misuse the copula だ.

2. Reading Speed (読解対策)

When reading long, complex sentences, the indirect question clause often contains vital descriptive information. Train yourself to mentally bracket the entire clause (e.g., [〜どこで起きたか]) as one single piece of data. This prevents you from getting lost in translation and allows you to quickly identify the main action being performed (e.g., 述べる/to state, or 疑問に思う/to wonder).

3. Shadowing and Listening (聴解対策)

Indirect questions are frequently used in conversation recordings when one speaker is reporting information or asking someone to check a fact. Practice shadowing sentences containing this structure, focusing on the slight pause or intonation drop after the plain form verb and before the final main verb. This helps you parse the sentence structure in real-time.

Conclusion: Achieving Fluency with Sophisticated Structures

Mastering the [疑問詞] + V/N/Adj (Plain) + か structure is a key milestone in your journey toward advanced Japanese. It moves you away from simple, disjointed statements and allows you to construct fluid, sophisticated sentences required for academic, professional, and advanced conversational settings.

To summarize, always remember the core rules:

1. The entire clause acts as a noun phrase carrying the information.
2. The verb/adjective/noun inside the clause must be in the plain form.
3. This structure is essential when dealing with verbs of knowing, communicating, or deciding (知る, 教える, 決める, etc.).

By consciously identifying and practicing indirect questions, you will sharpen your grammatical accuracy, boost your comprehension speed, and ultimately be well-prepared to tackle the challenges of the intermediate and advanced JLPT levels. Keep drilling these patterns, and your Japanese will become undeniably more natural and powerful!

頑張ってください！ We believe in your success! 

Need JLPT training platform? IPPO is free tool certified by the pro Japanese teachers.