【～が要る】　Is 要る an adjective? Why not を？


「要る」をneedと訳してしまうと、どうして「～を要る」にならないのか、わかりません。




要る is an **intransitive _verb_** that means "to be necessary" or "to be
needed" rather than "to need". (No i-adjective ends with る in Japanese.)
That's why we mark the needed thing using が rather than を. For example, the
very literal translation of お金が要る is "Money is needed", but in English, it's
usually more natural to translate this as "[I] need money". Likewise, "要る?" is
usually translated as "Do you want/need it?", but its literal translation is
"Is it necessary?".

(The link by Chocolate explains a rather exceptional case where 要る is used as
part of the [`AをBと + verb`
pattern](https://japanese.stackexchange.com/a/55169/5010), but this doesn't
mean 要る can take を alone.)

