〜を機に / 〜を機として

taking … as an opportunity; on the occasion of …; … became the trigger for

〜を機に names an event that became a turning point: because that event happened, the speaker took a new action or something new began. 機 (き) means "chance, occasion". The event itself is not the cause; it is the moment the speaker used to make a change.

Formal but very common: announcements, business writing, life-event stories (結婚・退職・引っ越し・出産), and news about policy changes. 〜を機として is a stiffer written variant. In casual speech 〜をきっかけに is more usual.

• N + を機に
• N + を機として (more formal, written)
• Vた / Vる + の + を機に (退職したのを機に)
• Typical nouns: 結婚・出産・退職・卒業・転勤・事故・事件・受賞

1. 01

   結婚を機に、都心から郊外へ引っ越した。

   けっこんをきに、としんからこうがいへひっこした。

   Taking marriage as the occasion, we moved from the city center to the suburbs.

   Marriage is the occasion; moving house is the new action the couple decided on.

2. 02

   退職を機に、長年の夢だった世界一周の旅に出た。

   たいしょくをきに、ながねんのゆめだったせかいいっしゅうのたびにでた。

   On retiring, I set out on the round-the-world trip that had long been my dream.

   退職 + を機に + a long-held plan is a very common life-story pattern.

3. 03

   この事故を機として、安全基準が見直された。

   このじこをきとして、あんぜんきじゅんがみなおされた。

   Taking this accident as a trigger, the safety standards were reviewed.

   を機として is the formal written version, typical of official reports about reforms.

4. 04

   子供が生まれたのを機に、たばこをやめた。

   こどもがうまれたのをきに、たばこをやめた。

   When my child was born, I took the opportunity to quit smoking.

   A clause can be used with の + を機に.

5. 05

   創立五十周年を機に、会社は新しいロゴを発表した。

   そうりつごじっしゅうねんをきに、かいしゃはあたらしいロゴをはっぴょうした。

   On the occasion of its fiftieth anniversary, the company unveiled a new logo.

   Anniversaries and milestones are natural occasions for を機に.

• 〜をきっかけに

  Same idea, but more casual and everyday. を機に sounds more formal and is preferred in writing. Compare side by side

• 〜を契機に

  The stiffest of the three; typical of newspapers and official documents. Often used for large social changes rather than personal life events. Compare side by side

• 〜を境に

  Marks a dividing line after which things are different. を境に describes a change that happened; を機に describes an action someone chose to take. Compare side by side

• ✗

  結婚を機に、幸せになった。

  ✓

  結婚を機に、家を買った。

  Why

  The main clause should be a deliberate new action or a clear new start, not a vague result or feeling.

• ✗

  雨が降ったのを機に、試合が中止になった。

  ✓

  雨が降ったので、試合が中止になった。

  Why

  を機に is not a cause. A cancellation forced by rain is a plain cause-and-effect, so use ので / ため.

• ✗

  退職を機会に、旅に出た。

  ✓

  退職を機に、旅に出た。

  Why

  The grammar pattern uses 機 alone. 機会 is a normal noun ("opportunity") and does not form this construction.

Set phrases: これを機に ("taking this as an opportunity") and 〜を機に〜を始める / やめる / 見直す. The event is usually something significant and positive or neutral (a milestone), though accidents can trigger reforms (事故を機として). In speeches you will hear 本日の〜を機に、〜てまいります, a polite way to announce a new commitment.