In a report I handed in earlier this week, my professor corrected my sentence to


from 「伴い」. Is there a practical difference between the two? ALC shows a bunch of examples with essentially identical usage.

Here's the definition from 大辞林:

  1. 一緒に行く。引き連れて行く、またつき従って行く。「秘書を伴って行く」「父に伴って博物館に行く」

  2. ある事柄に応じて生ずる。「危険を伴う手術」「人口増加に伴う住宅問題」

It seems like に and を are being used interchangeably. Is there a rule of thumb for when to use which?

  • 3
    Although I do not think that 時間に伴い is very natural, I consider 時間を伴い as simply incorrect. I would write 時間の経過に伴い, 時間とともに, or something else. Nov 11, 2011 at 14:43

1 Answer 1


Their nuances are different, and you need to decide each time which is appropriate.

When を is used:

  • 秘書を伴って

    You are the main person, and your secretary is accompanying you.

  • 危険を伴う手術

    The main event is surgery, and some danger comes with the surgery.

When に is used:

  • 父に伴って

    Dad is the main person, and you are accompanying him.

  • 人口増加に伴う住宅問題

    The main (first) event is population growth, then housing problem comes after that.

With 時間を伴う or 時間に伴う, "something happens with the passage of time", so time comes first, then something happens, therefore 時間に伴って is appropriate. See also Tsuyoshi Ito's comment.


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