Public bathhouse · Open
Kojigoku Onsen-kan
- Day-use bathing
- Yes
- Fee
- ¥500checked 2026-10-09
- Hours
- 9:30–19:00checked 2026-10-09
Photo information
Save to passport
Official classification
Spring type (therapeutic classes)
Official spring-type name (as recorded)Simple sulfur hot spring, hydrogen-sulfide type (hypotonic, weakly acidic, hot) — Kojigoku source
- Source temperature
- 51.1°C
- pH
- 4.3
- Flow rate
- Unconfirmed
- Radon
- Unconfirmed
Appearance & feel
Water colour · Feel
Milky white
Colour and feel are listed only where a source states them. They vary by day and by bath.
What makes it special
A highland sulfur spa where the inns stand right beside the Unzen Hells, a field of steam vents roaring out of bare ground.
Facilities in this area
Facilities come from the register (Wikipedia, OpenStreetMap, official sites). Those marked "natural spring unconfirmed" are listed on the basis of their name only.
Public bathhouse · Open
Unzen Shinyu Onsen-kan
- Day-use bathing
- Yes
- Fee
- ¥200checked 2026-10-09
- Hours
- 9:00–22:00checked 2026-10-09
Hotel · Open
Unzen Onsen Seiunso
- Day-use bathing
- Yes
- Fee
- Unconfirmedno check date
- Hours
- Unconfirmedchecked 2026-10-09
Getting there
Reachable by public transport
From JR Isahaya Station, Shimatetsu buses take about 80 minutes. From Nagasaki Station a direct Nagasaki Prefectural Bus takes about 100 minutes (three a day), and a fixed-fare bus from Nagasaki Airport via Isahaya takes about 100 minutes.
- Getting there
- Isahaya Station · 80
- Getting there
- Three direct buses a day from Nagasaki Station
- Checked
- 2026-10-09
About the water
Unzen's water is sulfurous and weakly acidic: the notice for the Kojigoku source gives simple sulfur spring, pH 4.3, 51.1 °C at the source. It runs milky white, and the whole town smells faintly of sulfur. The heat comes from the same underground source as the gas venting in the Hells next door. Claims about how your skin will feel come from the inns themselves, and we make no medical claims; the Kojigoku notice lists indications for bathing such as neuralgia and chronic skin conditions.
Indications (as posted on the analysis)
Posted at Kojigoku Onsen-kan (bathing): neuralgia, sprains, chronic gynaecological complaints, joint pain, poor circulation, diabetes, stiff joints, frozen shoulder, fatigue, chronic skin conditions, muscle pain, haemorrhoids, cuts, motor paralysis, convalescence, arteriosclerosis, bruises, chronic digestive complaints, high blood pressure, general health
Indications are an official statement based on the water analysis, not a guarantee of treatment. They are kept separate from opinions.
| Source | Source temperature | pH | Radon | Checked |
|---|---|---|---|---|
| Unzen Onsen (Kojigoku) | 51.1 | 4.3 | Unconfirmed | no check date |
Three things not to miss
Photo information
Unzen Hells (Unzen Jigoku)
Directly behind the hot spring town A stretch of ground where hot water and volcanic gas burst from cracks in the rock, crossed by walking trails. Individual vents, such as Seishichi Jigoku, have their own names.
Before you even get in a bath you can see, and smell, where the heat comes from. Few spa towns have a geothermal field like this a short walk from the inns.[2][1]
Kojigoku Onsen-kan
Edge of town, 5 minutes on foot from Seiunso A public bathhouse first opened in 1919. The present wooden building dates from 1993, yet its walls have already turned black from the minerals in the steam. It sits directly over its source and is fed milky, simple sulfur water (pH 4.3, 51.1 °C). Adults 500 yen.
Kojigoku is said to have the largest flow in Unzen, and here you can bathe in it without staying the night. It is the clearest taste of what Unzen is known for: cloudy, sulfurous water.[3][5]
Unzen Shinyu Onsen-kan
Near the Hells trail, 3 minutes from the Unzen Oyama no Johokan bus stop A neighbourhood bathhouse built around 1957 and kept going by local residents. It is simply a stone-tiled bathroom and a changing room, and costs 200 yen for adults. There is no shampoo, so bring your own.
It is close to its source and known for plentiful water. Hikers coming down from the peaks and local regulars drop in, giving you a side of Unzen away from the sightseeing.[4]
The story
A mountain of faith and healing
Unzen's springs are said to have been in use for over 1,300 years, first as a place of worship and healing. According to Wikipedia, the story begins in 701 when the monk Gyoki founded Manmyoji temple. Today a town of inns sits on a highland basin, wrapped in white steam and the smell of sulfur.[1][7]
The Hells and the martyrs
The Hells carry a dark history. According to the Japan National Tourism Organization, between 1627 and 1632 the Shimabara lord Matsukura Shigemasa and his successors tortured Christians in the boiling water here, and many died. A memorial to the martyrs still stands among the vents.[2]
From foreign summer retreat to national park
From the Meiji era to the early Showa era, Unzen thrived as a summer retreat for foreigners, drawn by the cool air at around 700 m. In 1934 it became one of Japan's first national parks. The Kojigoku public bathhouse opened in the same period, in 1919.[1][3][7]
Going solo
Easy for solo travellersUnconfirmed
Weekend / peak restrictionsUnconfirmed
Where to eat dinnerUnconfirmed
Private bathYes
checked 2026-10-09
Through the year
Recommended months
JanFebMarAprMayJunJulAugSepOctNovDec
Months open
JanFebMarAprMayJunJulAugSepOctNovDec
"Recommended" and "open" are recorded separately. Check the season for seasonal springs.
Jul · Aug — At about 700 m, Unzen was a summer retreat for foreign residents from the Meiji era to the early Showa era
Jan · Feb · Dec — The Hells steam all year; check road conditions before driving in winter
Food, culture & experiences
Unzen Hells
Walking trails loop through the steaming ground[2]
A short walk from the townObama Onsen
A seaside spa in the same city, with sources said to reach 105 °C and chloride water. About 5 km and 700 m lower than Unzen[1]
About 5 km (by car)Editors' guide
Start with a loop of the Hells to get a feel for the steam and the sulfur. Then bathe in the milky water at Kojigoku Onsen-kan, and if you have time, at Shinyu Onsen-kan where the locals go. Bring your own soap and shampoo. Both close on Wednesdays (Kojigoku opens on holidays), so avoid a Wednesday day trip.
The "editors' guide" above is written by the editors from sources; it is not a visitor's opinion.
Photo gallery
Visitor reviews
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Overview
Unzen Onsen is a geothermally heated volcanic hot spring field in the Unzen Mountains in Nagasaki prefecture in Japan. It was known of for many years, and in the 1910s was developed into a hot spring community because of its many springs. In 1934 the area was designated as the first national park in Japan. The hot springs are surrounded by an area known as the Hells (jigoku). These barren fields of hot springs contain many steam vents, bubbling mud pits and fumaroles. After the Shimabara Rebellion the Hells were used to execute Christian rebels. Today, paved trails lead visitors through the Hells. In an older, now dormant hot springs field, paths lead to the Manmyoji Temple and to the Unzen Disaster Museum, that commemorates the eruptions that occurred in the 1990s in which 12,000 people were evacuated and over 40 people perished.
This overview is based on the lead section of the English Wikipedia article (CC BY-SA 4.0). View original page
Onsen areas nearby
Unconfirmed & notes
- Number of tubs by gender and notices on free-flowing water, added water, heating or recirculation at Kojigoku and Shinyu were not confirmed
- Seiunso's day-bathing fee, hours and solo-stay terms were not confirmed
- The Yunosato public bath could not be confirmed and is not listed
Sources
- Find UNZEN 温泉(雲仙観光情報サイト)雲仙観光局 · 2026-10-09
- Unzen Hells (Japan Travel)日本政府観光局(JNTO) · 2026-10-09
- 小地獄温泉館(雲仙温泉 青雲荘 公式)雲仙温泉 青雲荘 · 2026-10-09
- 雲仙新湯温泉館(Find UNZEN)雲仙観光局 · 2026-10-09
- 雲仙温泉 青雲荘(Find UNZEN)雲仙観光局 · 2026-10-09
- アクセス(Find UNZEN)雲仙観光局 · 2026-10-09
- 雲仙温泉 - Wikipedia(日本語版)Wikipedia · 2026-10-09
Register sources
- 雲仙温泉 - Wikipedia(日本語版)Wikipedia · CC BY-SA 4.0 · 2026-10-09
- Wikidata Q11660005Wikidata · CC0 · 2026-10-09
Data status
Name & locationPublishedCoordinatesPublishedSpring typePublishedPhotosPublishedFacilitiesPublishedVisiting info (dated)PublishedEditorial articlePublished
Updated 2026-10-09
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