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Onsen vs sento: what is the difference?

An onsen is defined by its water: the Onsen Act sets a temperature or substance test for water or gas from underground. A sento is defined by its business: a public bath under the Public Bath Act, with its fee controlled under the Price Control Ordinance.

Written by Max, checked 2026-10-21

Oshiage Onsen Daikokuyu

Photo: Totti, CC BY-SA 4.0

Our database, checked 2026-10-30.

What is the difference between an onsen and a sento?

An onsen is defined by its water: under the Onsen Act it is warm water, mineral water, steam or gas (other than hydrocarbon natural gas) from underground with a temperature or a substance listed in the Act's table. A sento is defined by its business: a general public bath under the Public Bath Act, which local residents use for everyday hygiene, with its bath fee controlled under the Price Control Ordinance.

The Public Bath Act defines a public bath as a facility that bathes the public using warm water, sea water, onsen or similar, so the two overlap: a public bath can run on onsen water. JNTO's shorthand is that a sento just uses normal heated water instead of natural geothermal water in its baths. Tap-style faucets for hot and cold water arrived in the sento bathroom in 1927, the Tokyo Sento Association's history notes. The temperature and substance test is on what is an onsen.

Onsen Hopper lists 1,475 baths that take day visitors; 1,397 state a price, the median is ¥750 and 32 are free, checked 2026-10-30.

What is a Japanese bath house?

Japanese law calls a bath house open to the public a public bath, koshu yokujo: a facility that bathes the public using warm water, sea water, onsen or similar. Running one needs the prefectural governor's permission under the Public Bath Act.

The Tokyo Sento Association explains that the Act also covers kenko land leisure baths and saunas, but a sento falls in the general public bath category, as a facility local residents need for public hygiene and welfare. Baths in lodgings licensed under the Ryokan Business Act, such as inns and hotels, fall outside the Public Bath Act.

What is a super sento?

Hiroshima Prefecture places so-called super sento among the public baths outside the general category, with no regulation of the bath fee. JNTO describes super sento as having a huge variety of baths and other amenities like massages and steam rooms.

Asaka City's page names saunas, large leisure bath complexes (kenko land) and super sento among the other public baths, the ones the Price Control Ordinance does not apply to. Fukushima Prefecture notes that its sento price cap does not apply to so-called super sento.

How much does a sento cost?

In Tokyo an adult, age 12 and over, pays 600 yen including tax. That is the price from 1 August 2026, when the adult fee rose by 50 yen.

The fee is capped: for general public baths the governor sets an upper limit, the toseigaku. Osaka Prefecture notes that the cap is only an upper limit and each operator decides its actual fee. Some sento have a ticket vending machine for entry tickets, the Tokyo Sento Association says.

For comparison, the median day-use price among the 1,397 onsen on Onsen Hopper that state one is ¥750, and 32 are free, checked 2026-10-30. Cheap onsen lists the ones at ¥500 or less.

How many sento are there in Tokyo?

About 430 sento were operating in Tokyo as of November 2024, nearly all of them members of the Tokyo Sento Association. The first in Edo, as Tokyo was then called, was built in 1591 by Zenigame Bridge, near today's Tokiwa Bridge, according to the Keicho Kenmonroku of 1614.

Onsen inside Tokyo, and day trips out of it, are on Tokyo.

Which should I visit?

Both are shared spaces, and JNTO says good bathing manners are essential in both. Onsen hotels provide towels and soap; at a small local sento bring your own.

Some are hole-in-the-wall places off side alleys, visible only by their distinctive signs. The painted backdrops of Mount Fuji and the like seen in Tokyo sento are the work of a few painters today, the Tokyo Sento Association says. One finishes the large wall canvas in about five hours before opening time, the association says. The rules in order are on onsen etiquette. Paid entry at inns and bathhouses is on how day use works.

Questions

Is a sento an onsen?

Not by definition: a public bath may use warm water, sea water, onsen or similar, so a sento can run on onsen water but need not. JNTO's shorthand is that a sento just uses normal heated water instead of natural geothermal water.

Do I need my own towel at a sento?

At a small local sento, yes: bring your own soap and towels, while onsen hotels provide them. If you forget, the Tokyo Sento Association says most sento sell mini soap, mini shampoo, mini conditioner and towels.

Is a super sento price-controlled?

No: a super sento is a public bath outside the general category, and its bath fee is not regulated. The governor's cap applies to general public baths, the sento.

Sources
  1. e-Gov Law Search (Japan), 温泉法, checked 2026-10-21
  2. Ministry of Health, Labour and Welfare, 公衆浴場法概要, checked 2026-10-21
  3. Ministry of Health, Labour and Welfare, 公衆浴場法(昭和23年法律第139号), checked 2026-10-21
  4. Japan National Tourism Organization, Onsen Hot Springs - On Tattoos and Etiquette, checked 2026-10-21
  5. Tokyo Sento Association, 銭湯の歴史 | 【公式】東京銭湯／東京都浴場組合, checked 2026-10-21
  6. Tokyo Sento Association, 銭湯Q&A, checked 2026-10-21
  7. Hiroshima Prefecture, 公衆浴場の入浴料金について, checked 2026-10-21
  8. Japan National Tourism Organization, Enjoy Bath Culture in Japan, checked 2026-10-21
  9. Asaka City, 公衆浴場（市内の銭湯）, checked 2026-10-21
  10. Fukushima Prefecture, 普通公衆浴場入浴料金統制額の改定について, checked 2026-10-21
  11. Tokyo Sento Association, 入浴料金のお知らせ, checked 2026-10-21
  12. Osaka Prefecture, 公衆浴場入浴料金統制額の指定について, checked 2026-10-21
  13. Tokyo Sento Association, 銭湯の入り方 | 【公式】東京銭湯／東京都浴場組合, checked 2026-10-21
  14. Tokyo Sento Association, 東京都浴場組合について, checked 2026-10-21

Made by Max for Onsen Hopper · Where the facts come from