I-adjectives: affirmative and negative
Describe things as expensive, difficult, or hot—and learn how to say they are not.
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An i-adjective can finish a plain Japanese sentence by itself. この 車 は 高い means “This car is expensive.” English needs “is” before “expensive”; Japanese does not need a separate equivalent here. Add です for a polite sentence: 高い です.
To make an i-adjective negative, change the adjective itself. Remove the final い and add くない. Do not use the noun ending じゃ ない directly after an i-adjective.
remove the final い and add くない
- 高い → 高くない
- 安い → 安くない
- 難しい → 難しくない
Exception
- いい → よくない — いい (“good”) is irregular: use よくない, not いくない.
For the polite negative taught here, keep です after the changed adjective: 高くない です. When you learn the past form, the adjective will change again. Its ending carries the negative or past meaning in these patterns.
Examples
この 車 は 高い です。
This car is expensive.
この 本 は 高くない です。
This book is not expensive.
日本語 は 難しい です。
Japanese is difficult.
この コーヒー は 熱くない です。
This coffee is not hot.