優しい vs 易しい
JLPT N5 vocabulary · what is the difference?
Both are read やさしい, and only the kanji tells them apart: 優しい means kind or gentle to people, and 易しい means easy to do or understand. 優しい先生 is a kind teacher; 易しい問題 is an easy question. In speech the context decides, and in writing 易しい is often replaced by kana やさしい or by 簡単な.
When to use each
優しい
やさしい
Use 優しい about people and how they treat others — kind, gentle, considerate. It also describes gentle voices and things that are gentle on the body or the environment.
彼女はだれにでも優しいです。
かのじょはだれにでもやさしいです。
She is kind to everyone.
この洗剤は手に優しい。
このせんざいはてにやさしい。
This detergent is gentle on the hands.
易しい
やさしい
Use 易しい about tasks and material that take little effort to do or understand: questions, books, explanations. It is the opposite of 難しい.
この問題は易しいので、すぐできます。
このもんだいはやさしいので、すぐできます。
This question is easy, so I can do it right away.
初心者には易しい日本語の本がいいです。
しょしんしゃにはやさしいにほんごのほんがいいです。
For beginners, easy Japanese books are good.
Sentences where only one works
優しい先生に易しい問題を出してもらった。
やさしいせんせいにやさしいもんだいをだしてもらった。
The kind teacher gave me an easy question.
The same pronunciation twice in one sentence, and only the kanji separates the kind teacher from the easy question.
お年寄りに優しい町です。
おとしよりにやさしいまちです。
It's a town that is kind to elderly people.
The 〜に優しい pattern means considerate toward someone. 環境に優しい, eco-friendly, works the same way.
この説明は易しくて分かりやすい。
このせつめいはやさしくてわかりやすい。
This explanation is easy and clear.
Ease of understanding, so 易しい. Written with 優 it would claim the explanation is kind-hearted.
言うは易く行うは難し。
いうはやすくおこなうはかたし。
Easier said than done.
A classical proverb where 易 keeps its 'easy' sense — a useful hook for remembering which kanji is which.
Common mistakes
優しい問題でした。
易しい問題でした。
Picking the wrong kanji when typing or writing is the real mistake here, and it makes the sentence say the question was kind-hearted. Spoken aloud it is fine, which is why learners never notice the error until they write.
易しい先生が好きです。
優しい先生が好きです。
Reversed the other way: 易しい先生 reads as a teacher who is easy to do, which is not a meaning Japanese has for a person.
Frequently asked questions
How do I know which one someone means when they speak?
By what the adjective describes. A person is almost always 優しい, and a question, book or explanation is 易しい. Ambiguity is rare in practice.
Which kanji should I write for 'easy'?
易しい is correct, but in practice many writers use kana やさしい or switch to 簡単な to avoid confusion. 簡単 is the safest choice for beginners.
What does 環境に優しい mean?
Environmentally friendly. The 〜に優しい pattern extends the 'kind' sense to things that go easy on something — 体に優しい食事 is food that is gentle on your body.