かたい (硬い・固い・堅い): One Sound, Three Kanji
One sound, several kanji
When you meet かたい, the trouble isn't the meaning — it's choosing the kanji. The same reading writes three close cousins, and even native speakers sometimes hesitate. The good news: they share a single mental image. Something かたい resists change. It won't bend, it won't squish, it won't come loose, it won't fall apart.
What kind of resistance you mean decides the kanji:
- 硬い — resists pressure. It's physically hard and stiff (opposite of やわらかい, "soft").
- 固い — resists coming loose or moving. It's firm, tight, set in place (opposite of ゆるい, "loose").
- 堅い — resists failure. It's sturdy, dependable, low-risk (a person or a choice you can trust).
Hold that one image — "resists change" — and the three kanji stop feeling random. Below we take them most-common-first, then give you a rule of thumb and the look-alike traps at the end.
The meanings, most common first
1. Physically hard / stiff (硬い)
このパンは硬くて食べられない。
この パンは かたくて たべられない。
This bread is so hard I can't eat it.
硬い is the opposite of やわらかい (soft). Use it for things you can press or bite.
2. Stiff / tense (of expression or movement) (硬い)
ヤッタンは試験の前で表情が硬かった。
ヤッタンは しけんの まえで ひょうじょうが かたかった。
Yattan had a stiff expression before the exam.
A 硬い face or 硬い movement = tense, not relaxed. Same kanji as 'physically hard.'
3. Firm / unshakeable (a promise, a will) (固い)
モチとヤッタンは固い約束をした。
モチと ヤッタンは かたい やくそくを した。
Mochi and Yattan made a firm promise.
固い約束 = a promise that won't be broken. Also 固い決心 (firm resolve).
4. Tightly fastened / tied (固い → 固く)
先生はひもを固く結んだ。
せんせいは ひもを かたく むすんだ。
Sensei tied the string tightly.
The adverb form 固く means 'firmly, tightly.' Opposite of ゆるい (loose).
5. Stubborn / inflexible (頭が固い) (固い)
ヤッタンの弟は頭が固くて、新しいやり方を嫌がる。
ヤッタンの おとうとは あたまが かたくて、あたらしい やりかたを いやがる。
Yattan's little brother is stubborn and dislikes new ways of doing things.
頭が固い (lit. 'hard head') = stubborn, set in one's ways.
6. Steady / reliable / low-risk (a job, a choice) (堅い)
モチは堅い仕事に就きたいと思っている。
モチは かたい しごとに つきたいと おもっている。
Mochi wants to get a steady, secure job.
堅い here means dependable and low-risk — a 'safe bet,' not a fun gamble.
7. Serious / dependable (of a person) (堅い)
先生はとても堅い人で、約束を必ず守る。
せんせいは とても かたい ひとで、やくそくを かならず まもる。
Sensei is a very dependable person who always keeps his promises.
A 堅い person is sober, trustworthy, and serious — the opposite of frivolous.
All three keep coming back to "resists change": 硬い resists pressure, 固い resists coming loose, 堅い resists failing you. You don't have to memorize each use separately — decide what kind of resistance you mean, and the kanji follows.
Common collocations worth memorizing
Some かたい phrases are fixed enough that natives reach for the same kanji every time. Learn these as chunks:
| Collocation | Reading | Kanji | Meaning |
|---|---|---|---|
| 硬いパン | かたいパン | 硬 | hard bread |
| 表情が硬い | ひょうじょうが かたい | 硬 | stiff / tense expression |
| 固い約束 | かたい やくそく | 固 | firm promise |
| 頭が固い | あたまが かたい | 固 | stubborn |
| 固く結ぶ | かたく むすぶ | 固 | to tie tightly |
| 堅い仕事 | かたい しごと | 堅 | a steady, secure job |
| 堅い人 | かたい ひと | 堅 | a serious, reliable person |
Kanji & related かたい words
Each kanji carries its own flavor — and that's exactly what tells you which to write:
- 硬 ("hard, rigid") → physical hardness and stiffness: 硬い金属, 硬い表情. Antonym: 柔らかい (やわらかい).
- 固 ("solid, set") → firmness, tightness, being fixed in place: 固い約束, 固く結ぶ, 頭が固い. Antonym: 緩い (ゆるい).
- 堅 ("sturdy, sound") → reliability and low risk: 堅い仕事, 堅い人. Think "dependable."
Two quick notes. First, there's a near-identical adjective, かたい written 難い (N3+), meaning "hard to do" — it attaches to verb stems (信じ難い = "hard to believe") and is a different word, so don't confuse it with the three above. Second, the related noun 固まる／固める (かたまる／かためる, "to harden / to make firm") comes from the same 固 family — handy to recognize but above N5.
硬い vs 固い vs 堅い — choosing the kanji
This is the whole game. The trick is to ask what kind of resistance you mean:
| Form | Core idea | Example |
|---|---|---|
| 硬い | Physically hard / stiff — resists pressure | 硬いパン = hard bread; 表情が硬い = stiff expression |
| 固い | Firm, tight, set in place — resists coming loose | 固い約束 = firm promise; 固く結ぶ = tie tightly; 頭が固い = stubborn |
| 堅い | Sturdy, reliable, low-risk — resists failing you | 堅い仕事 = steady job; 堅い人 = dependable person |
Rule of thumb: Can you touch it and feel it's hard? → 硬い. Is it fastened, fixed, or unbreakable (a promise, a knot, a stubborn head)? → 固い. Are you describing how trustworthy or low-risk a person or choice is? → 堅い. And when none of those feels obviously right — or you just can't decide — write it in kana (かたい). That's not a cop-out; it's what plenty of native writers do, and it's never wrong.
Watch the antonyms, too — they confirm your choice: 硬い ↔ 柔らかい (soft), 固い ↔ 緩い (loose). If "soft" is the natural opposite, you want 硬い; if "loose" is, you want 固い.
Quick recap
- One sound, three kanji, one core image: resists change.
- 硬い = physically hard/stiff (↔ 柔らかい). 固い = firm/tight/set (↔ 緩い). 堅い = sturdy/reliable/low-risk.
- All three are い-adjectives: かたく, かたかった, かたくない.
- Touch-hard → 硬い; fastened/unbreakable → 固い; dependable → 堅い; unsure → write かな.
Your turn
Ready to test your N5 vocabulary in context?
Start the 5-question drill →Frequently asked questions
Is かたい a verb or an adjective?
かたい is an い-adjective. It conjugates like other い-adjectives: かたく (adverb), かたかった (past), かたくない (negative). This is true for all three kanji — 硬い, 固い, and 堅い.
Which kanji should I use for かたい?
Ask what kind of resistance you mean. Physically hard (like bread)? Use 硬い. Firm or tightly fixed (a promise, a knot, a stubborn head)? Use 固い. Reliable and low-risk (a steady job, a dependable person)? Use 堅い.
Is it okay to write かたい in hiragana?
Yes. When you're unsure which of the three kanji fits, writing かたい in kana is completely acceptable and very common — even native writers do it. You won't be marked wrong for it.
What are the opposites of かたい?
It depends on the meaning. 硬い (physically hard) is the opposite of 柔らかい (やわらかい, soft). 固い (firm, tight) is the opposite of 緩い (ゆるい, loose).