I understand that the word for police box is Koban or 交番 in kanji, but why is the signage always in roman letters - Koban.

My guess would be to make it easier for foreigners to read, but wouldn't they just put the English word instead - "police box"?

Just wondering if anyway knows of a real reason for this.

2 Answers 2


The answer is right on the 警視庁 (metropolitan police department)'s website.

Basically it says that it is common to use foreign words as-is if there is no similar cultural counterpart, using sumo and kabuki as examples. Koban is an unfamiliar idea in most cultures, so that's why they decided to go with using "koban" as is. The koban system has been introduced in the west.

They also make an effort to reinforce this on their English website.

While "police box" is often used as the closest translation, police boxes are actually very different from koban, in both size and purpose. The MPD probably wants to make this distinction. Also, not every Japanese resident can think up the words "police box" and this can hinder communication with a non-Japanese speaker; they would most certainly be able to point a lost tourist to the nearest "koban".

  • I did a quick Google search, but go figure the answer was right there. Thanks for hunting this down. Perfect answer!
    – Mac
    Commented Aug 21, 2018 at 12:53

I cant comment, but according to


The name kōban derives from the name of the earliest structure built in 1874, which were indeed simple boxes meant for standing watch (立番 tachiban) in rotation (交替 kōtai), thus creating a compound word consisting of kō (交) and ban (番).

Citied from here (archived version) I added the wikipedia cite since, the original is only in japanese.

  • 3
    But how does this explain why it's often written in Romaji?
    – muru
    Commented Aug 21, 2018 at 15:02
  • @muru it does not, but it certainly discredits the answer from jimmy. As stated I cant comment. =)
    – Git
    Commented Sep 24, 2018 at 7:18
  • @muru jimmys answer states that it is a borrowed word. The citation I got, states it is an original term. The only question remaining is, whose source to trust more.
    – Git
    Commented Sep 24, 2018 at 7:25
  • You misread that answer. It doesn't say koban is a borrowed word in Japanese. It says it's a loanword in English, like sumo. (Unless you think sumo is also a loanword in Japanese?)
    – muru
    Commented Sep 24, 2018 at 7:31

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