GrammarJLPT N5
→ question marker particle
か – Question Marker Particle
JLPT N5ParticleNeutral
The particle か is placed at the end of a sentence to turn a statement into a question, functioning much like a spoken question mark in Japanese. In polite speech (です/ます style), か is the standard and expected way to form questions. In casual speech, か can sound blunt, interrogative, or even aggressive depending on intonation, so casual questions often drop か entirely and rely on rising intonation alone, or use softer alternatives like の. Because Japanese does not require subject-verb inversion or any word-order change to form questions, か (or intonation) is the primary grammatical signal that a sentence is a question. When used in polite register, the sentence typically ends with ですか or ます-form + か. It is one of the first and most essential particles learners encounter.
Examples
Example #1
これは 本ですか。
Here か is attached to the end of the polite copula です to transform the statement これは本です (This is a book) into a yes/no question. No change in word order is needed; the particle か alone signals that the speaker is asking rather than stating. In written Japanese, a question mark is not strictly necessary when か is present, though it is sometimes added for clarity.Is this a book?
Structures
- Polite sentence
- Statement (です / ます form) + か
- Plain sentence (formal/written)
- Statement (plain form) + か
Common mistakes
A common mistake is using か in casual conversation with friends, where it can sound stiff, overly direct, or even confrontational — casual Japanese typically relies on rising intonation or the particle の instead of か. Another frequent error is placing だ before か in questions with nouns and な-adjectives; for example, saying 学生だか is incorrect — the correct polite form is 学生ですか, and in plain form the だ is simply dropped (学生か). Beginners also sometimes forget to include か in polite speech when a question word like なに or どこ is present, assuming the question word alone is sufficient, but in polite register か should still be used.
Related
の (question particle)かどうかかなでしょうかんですか