要する (yousuru) conjugation
to demand, to require, to take
要する (ようする, yousuru) is an irregular verb. Only する and 来る are truly irregular, and every learner meets them in week one. Every form below is tappable — hear it, then say it back.
Conjugation table
| Form | Plain (casual) | Polite (~ます) | When you use it |
|---|---|---|---|
| Dictionary / plain | 要する yousuru | 要します youshimasu | The form you look up. Also the casual present and future. |
| Plain negative | 要しない youshinai | 要しません youshimasen | “doesn’t / won’t”. From here it conjugates like an i-adjective. |
| Plain past | 要した youshita | 要しました youshimashita | The casual past — same ending as the te-form, with た/だ. |
| Plain past negative | 要しなかった youshinakatta | 要しませんでした youshimasendeshita | “didn’t”. The negative past, still i-adjective-shaped. |
| Te-form | 要して youshite | — | The connector: requests, linking clauses, ~ている. |
| Progressive (~ている) | 要している youshiteiru | 要しています youshiteimasu | “is ~ing”, or an ongoing resulting state. |
| Desire (~たい) | 要したい youshitai | 要したいです youshitaidesu | “want to ~”. Behaves as an i-adjective. |
| Volitional | 要しよう youshiyou | 要しましょう youshimashou | “let’s ~” / “I think I’ll ~”. |
| Potential | 要できる youdekiru | 要できます youdekimasu | “can ~”. What you could do; the object often takes が. |
| Passive | 要される yousareru | 要されます yousaremasu | “is ~ed”. Also the honorific and the suffering passive. |
| Causative | 要させる yousaseru | 要させます yousasemasu | Make or let someone do it. |
| Causative-passive | 要させられる yousaserareru | 要させられます yousaseraremasu | Be made to do it — the long one. |
| Imperative | 要しろ youshiro | 要してください youshitekudasai | Blunt order. Use ~てください in real life. |
| Prohibitive | 要するな yousuruna | — | “don’t!” — dictionary form + な. |
| Conditional (~ば) | 要すれば yousureba | — | “if ~”. General rules and hypotheticals. |
| Conditional (~たら) | 要したら youshitara | — | “if / when ~”. The everyday conditional. |
🔊 Tap any Japanese word to hear it spoken.
Why it conjugates this way
Only する and 来る are truly irregular, and every learner meets them in week one.
See the full rules on the verb conjugation guide.