I am quite confused regarding the differences between the usages of ように and ことに when they precede する/なる. Here are some examples:

  • 忘れ物をしないようにしましょう
  • 忘れ物をしないことにしましょう

In the previous example, I would think that in the 1st sentence the speaker would want the listeners to make sure there wouldn't be anything forgotten, while in the 2nd they would want the listeners to pay attention or to make an effort to not forget anything. Which makes sense to me because ようにする seems to have the meaning of "ある状態にする", while ことにする seems to have a meaning of "決意・努力をする" (please do tell me if I'm wrong). However, I can't tell the difference between the two if する is in continuative form, like in the following example:

  • 私は毎晩寝る前に日記を書くことにしています
  • 私は毎晩寝る前に日記を書くようにしています

When the following verb is なる, on the other hand, I can't tell the difference at all. For example, what's the difference between the following pairs of sentences?

  • ここの電気は人が通るとつくようになっています
  • ここの電気は人が通るとつくことになっています
  • 田中さんは家庭の事情で中国旅行には参加しないことになりました
  • 田中さんは家庭の事情で中国旅行には参加しないようになりました

What are the differences between ように and ことに?

  • Can you explain, with an example, what do you mean by "What if you add the te-form" (in the title)?
    – naruto
    Jul 12, 2021 at 1:34
  • I was just referring to the continuative form. I mentioned that specifically because ようにする・ようになる can have quite different meanings depending on if they are or not in continuative form. An example would be 今日はもう時間がないので、この仕事は明日することにします and 子供たちは、一日に2時間以上はテレビを見せないことにしています, in which the 1st one is a clear cut decision while the second is just something more like a habit or resolution. And, as I said, I couldn't see the difference between ように and ことに when the verbs were in continuative form. Jul 12, 2021 at 2:10
  • 1
    Ah, so you're referring to the -teiru form! I think "continuative form" normally refers to something different. The te-form is yet another form that is part of the -teiru form. Anyway, you can think of ことにしている as continuation of the "decided" state started in the past.
    – naruto
    Jul 12, 2021 at 4:04

1 Answer 1


In general, ~ようにする is simply about making/keeping something in(to) some state/situation described by the preceding verb. ~ことにする is about making a decision/rule/resolution.

  • 見えるようにする to make it visible
  • 見えるようになる to turn/become visible
  • 見えることにする to decide to make it visible
  • 見えることになる a decision is made to make it visible

Now let's look at each example:

  • 忘れ物をしないようにしましょう。
  • 忘れ物をしないことにしましょう。

The former is the natural choice. The latter means something like "Let's (make it a rule) not to forget anything (from now on)", which is an odd statement. It sounds like it was fine to forget something until now!

  • 寝る前に日記を書くようにしています。
  • 寝る前に日記を書くことにしています。

These are mostly interchangeable. The よう version is a neutral description of the speaker's habit. The こと version sounds a little stricter, like this is a private rule. See also: ことにする versus ようにする

  • ここの電気は人が通るとつくようになっています。
  • ここの電気は人が通るとつくことになっています。

The former is a neutral description of this mechanism. The latter implies "the light is supposed to be turned on" or "the rule is that this light will be turned on." When I hear something like this, I would wonder if the light is not working.

  • 田中さんは家庭の事情で中国旅行には参加しないようになりました。
  • 田中さんは家庭の事情で中国旅行には参加しないことになりました。

In this case, the こと version is the natural choice because it's about someone's decision. The former is not wrong, but may sound like someone is dodging responsibility. You have to use ようになる when you describe a natural phenomenon (e.g., 冬が近づき、夜に冷たい風が吹くようになりました).

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