At a glance
A にせよ B にせよ means "whether it is A or B". The same result or judgment applies either way. It is used mainly in formal speech and writing.
A にせよ B にせよ、[same result / judgment]
行くにせよ行かないにせよ、早めに決めてください。 Whether you go or not, please decide soon.
How to form it
にせよ attaches to plain forms. Nouns and な-adjectives take no だ.
| Attaches to | Form | Example |
|---|---|---|
| Verb | Plain form (dictionary, ない, た) + にせよ | 行くにせよ行かないにせよ |
| い-adjective | Plain form + にせよ | 高いにせよ安いにせよ |
| な-adjective | Stem (or stem + である) + にせよ | 好きにせよ嫌いにせよ |
| Noun | Noun (or noun + である) + にせよ | 雨にせよ雪にせよ |
Register: formal, written style.
にせよ comes from に + せよ. せよ is the classical imperative form of する. It literally means "let it be ~", which gives the meaning "even if it is ~".