Japanese Adjectives: i-adjectives and na-adjectives Explained
Japanese has two adjective types, and telling them apart unlocks correct descriptions, negatives, and past tense.
About the author
Luke McLaughlin created Constructing Language after living in Japan and later learning Mandarin Chinese from scratch. The lessons, games, and guides are built from that first-hand learner experience and checked against native-speaker course work with Hiro for Japanese and Xiang for Mandarin Chinese.
- Lived in Japan and studied Japanese through immersion and structured self-study.
- Learned Mandarin Chinese from scratch as an adult learner.
- Created the Construction Method: audio-first sentence building, grammar graphics, and active recall.
- Built Japanese course material with Hiro and Mandarin course material with Xiang, both native-speaker collaborators.
Two kinds of adjectives
Japanese adjectives come in two groups. i-adjectives end in い and conjugate by themselves. na-adjectives behave more like nouns and need な when they sit directly before a noun. Knowing which type a word is tells you how to make it negative, past, or polite.
- i-adjective: 高い (takai) — expensive / tall.
- na-adjective: 静か (shizuka) — quiet.
- Before a noun: 高い本 (takai hon) but 静かな部屋 (shizuka na heya).
i-adjectives conjugate themselves
For i-adjectives, change the ending rather than adding a separate word. 高い becomes 高くない (not expensive) and 高かった (was expensive). This is different from English, where the adjective never changes — in Japanese the adjective carries the tense and negation.
na-adjectives lean on です and the copula
na-adjectives express negation and past through the copula. 静かです (is quiet) becomes 静かじゃない (is not quiet) and 静かでした (was quiet). Treat na-adjectives as describing words that pair with the verb 'to be'.
Frequently Asked Questions
What is the difference between i-adjectives and na-adjectives?
i-adjectives end in い and conjugate on their own for negative and past tense. na-adjectives behave like nouns, take な before a noun, and form negatives and past with the copula (です / じゃない / でした).
How do you make a Japanese adjective negative?
For i-adjectives, change い to くない (高い → 高くない). For na-adjectives, use じゃない or ではない after the adjective (静か → 静かじゃない).