主客転倒

しゅかくてんとう, しゅきゃくてんとうshukakutentou

noun · suru verb

1. reversing the order of (relative) importance (of)
2. putting the cart before the horse
3. the tables being turned
4. mistaking the insignificant for the essential
5. mistaking the means for the end

Study it in Yanamino