Recently came upon sentences where the causative form is used to make a suru-verb a transitive one.

eg. この城を完成させるのに、...

Are all suru verbs, intransitive by default? If so, does this use of the causative form apply to all suru-verbs?


2 Answers 2


Update to previous comment

Transitivity/intransitivity is a function of whether the verb takes a direct object or not. So as long as the する verb can take a direct object, it can be said to be transitive.

However, having done a little bit of research on this now, it seems there are many する words that are called "ergative verbs", or 能{のう}格{かく}動{どう}詞{し}. Such verbs can be both transitive and intransitive, as T.Allred already mentioned. 完成する would fall into this category. Others would include the following, as per Japanese Wikipedia:


Unfortunately, it seems that the typically straightforward rules of conjugation in Japanese fall apart when it comes to transitive/intransitive する verbs. Based on everything I've been able to find on the subject, it seems that the best way to determine the status of a する verb is to A) find as many sample sentences as you can (via jisho.org, etc) to determine the most common usage, or B) rely on an actual comprehensive physical Japanese dictionary, as they apparently make notations regarding the status of each verb.

  • Isn't される the passive conjugation of する, though? Or are you saying that the passive conjugation acts as the intransitive conjugation, which would make me skeptical but I wouldn't completely disagree.
    – tcallred
    Commented May 18, 2017 at 21:14
  • Yeah, after a bit of research, I think I'll have to amend my original comment. While there are certain cases when it plays a dual role, it seems that it's kind of a case-by-case situation and certainly not a rule.
    – TFlo83
    Commented May 19, 2017 at 1:20

A suru-verb can be either transitive or intransitive depending on the context and the usage. In the case with 完成 it can be either one. But according to this reference 完成 is most used as intransitive so they use the causative to change it. japanese.stackexchange.com/q/27454/9749

Usually causitvity does not affect the transitivity of a verb but this may be an exception.

  • hmm....I'm not sure why you would say that 完成する is inherently intransitive. Transitivity is determined by whether the verb can take a direct object, which 完成する most certainly can. As in, 私はこのプロジェクトを完成しました。"I completed this project."
    – TFlo83
    Commented May 18, 2017 at 19:38
  • You know, I thought about that same thing and I think you're totally right. I think I thought about the times I've heard 完成 and I could only think of the times it was used intransitively. I will make an edit. Thank you.
    – tcallred
    Commented May 18, 2017 at 19:45
  • Related: japanese.stackexchange.com/q/27454/9749
    – Blavius
    Commented May 18, 2017 at 19:47
  • 1
    I feel 完成 is 95% intransitive and only 5% transitive. 私はこのプロジェクトを完成させました sounds more natural to me.
    – naruto
    Commented May 19, 2017 at 23:36

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