What it means
いずれにせよ presents a conclusion or decision as valid regardless of the circumstances, alternatives, or outcome previously mentioned. It is used as a sentence-level adverb, usually at the beginning of a sentence or clause, and means “in any case,” “regardless,” or “either way.” It is more formal and deliberate than ordinary conversational alternatives, so it is especially common in writing, presentations, discussions, and reasoned statements. The expression itself does not change for politeness; the clause that follows it can be made familiar or polite.
Usage note
いずれにせよ is often used after a preceding statement that introduces uncertainty, alternatives, or conditions, but the preceding statement can be omitted when the context is clear. Do not confuse it with いずれにしても, which has a very similar meaning and usage.
How to use it
いずれにせよ、私たちは来週その計画を実行します。
In any case, we will carry out that plan next week.
いずれにせよ、私たちは来週その計画を実行する。
In any case, we will carry out that plan next week.
Example sentences
結果が予想より良くても悪くても、いずれにせよ計画の見直しは必要だ。
Whether the result is better or worse than expected, in any case, a review of the plan is necessary.
展示会が予定どおり開かれるか延期されるかはまだ決まっていないが、いずれにせよ、来場者は事前に入場券を購入しなければならない。