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Japanese Adjectives: い-Adjectives vs な-Adjectives

Japanese adjectives come in two types: い-adjectives and な-adjectives. They conjugate differently for tense, negation, and te-form connections.

い-adjective conjugation

い-adjectives end in い and conjugate by modifying that final い. Present: そのまま. Past: い→かった. Negative: い→くない. Past negative: い→くなかった. Te-form: い→くて.

今日は寒い。きょうはさむい。Today is cold.
昨日は寒かった。きのうはさむかった。Yesterday was cold.
今日は寒くない。きょうはさむくない。Today is not cold.

な-adjective conjugation

な-adjectives behave like nouns. Add だ/です for assertion, だった for past, じゃない for negation. Te-form: add で.

東京は便利だ。とうきょうはべんりだ。Tokyo is convenient.
昔はもっと静かだった。むかしはもっとしずかだった。It used to be quieter.
彼は元気で明るい。かれはげんきであかるい。He is energetic and cheerful.

Common mistakes

Wrong

好きいです / 好きくない

Right

好きです / 好きじゃない — 好き is a な-adjective

好き (like), 嫌い (dislike), 有名 (famous), 綺麗 (pretty) are な-adjectives despite some ending in い. Memorise these exceptions.

Wrong

いい → いかった (past)

Right

いい → よかった (past)

いい is an irregular い-adjective. All conjugated forms use よ- stem: よくない, よくて, よかった.

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Frequently asked questions

How do I know if a Japanese adjective is い or な?

Most adjectives ending in い are い-adjectives. However, な-adjectives that end in い (like 好き, 嫌い, 綺麗, 有名) must be memorised as exceptions. When in doubt: if it sounds natural with だ directly after it, it's a な-adjective.

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