Is it an exception of 「ある」と「いる」の使い分け?


It is a basic grammar that「いる」is used to show the existence of something alive
and 「ある」is to show the existence of inanimate object in terms of 存在表現.

However, I found some people use "工夫がいる" instead of "工夫がある". Is it an
exception?

> 人に伝えるコトって **工夫がいる** んです！
>
> 細胞内の物質を積極的に移動させる **工夫がいる** 。




You are confusing 「居{い}る」 ("to exist") and 「要{い}る」 ("to be necessary").

In both of your two sentences, the verb is 「要る」, so it is just a normal usage.
「工夫がいる」, therefore, means " ** _(it) requires ingenuity_** ".

For the pronunciation of these two いる's and a few other verbs that are spelled
「いる」 if written in kana, see here:

[What is the intonation variation for 居る vs
要る?](https://japanese.stackexchange.com/questions/59295/what-is-the-
intonation-variation-for-%e5%b1%85%e3%82%8b-vs-%e8%a6%81%e3%82%8b/59296#59296)

