Public bathhouse · Open
Kami-yu communal bath
- Day-use bathing
- Yes
- Fee
- ¥300checked 2026-10-09
- Hours
- 6:00–22:00checked 2026-10-09
Photo information
Save to passport
Official classification
Spring type (therapeutic classes)
Official spring-type name (as recorded)Acidic, sulfur-bearing aluminium sulfate/chloride spring (old name: strongly acidic alum-vitriol hydrogen-sulfide spring)
- Source temperature
- 50.8°C
- pH
- 1.9
- 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
Strongly acidic sulfur water at pH 1.25–1.6. Three communal baths for 300 yen each, a vast riverside open-air bath, and in winter the snow monsters of Zao.
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
Shimo-yu communal bath
- Day-use bathing
- Yes
- Fee
- ¥300checked 2026-10-09
- Hours
- 6:00–22:00checked 2026-10-09
Public bathhouse · Open
Kawarayu communal bath
- Day-use bathing
- Yes
- Fee
- ¥300checked 2026-10-09
- Hours
- 6:00–22:00checked 2026-10-09
Day-use bath · Seasonal
Zao Onsen Great Open-Air Bath
- Day-use bathing
- Yes
- Fee
- ¥850checked 2026-10-09
- Hours
- 平日 9:30–17:00(最終受付16:30)/土日祝 9:30–18:00(最終受付17:30)checked 2026-10-09
Getting there
Reachable by public transport
From JR Yamagata Station, Yamako buses run to the Zao Onsen bus terminal (journey time not confirmed). In winter Yamako also runs a Sendai–Yamagata Zao service from Sendai Station's east exit. From Yamagata Airport there is a shared taxi to Zao Onsen. The communal baths are in the town, a short walk from the terminal.
- Getting there
- Yamagata Station (Yamagata Shinkansen / Ou Line) ·
- Through the year
- The great open-air bath closes late November to mid-April; a direct winter bus runs from Sendai Station
- Checked
- 2026-10-09
About the water
Zao's water, at pH 1.25–1.6, is among the most acidic in Japan, carrying sulfur, aluminium, sulfate and salt. Forty-seven sources in five groups yield about 5,700 litres a minute. The association describes milky water and a bath where the spring rises through the floor. Acid water gives a tightening, astringent feel on the skin, and sulfur springs have long been called skin-disease waters; the posted indications include cuts, burns and chronic skin complaints, while people with sensitive skin are warned off. The open-air bath's notices point out that the water itself erodes the floor and pool edges.
Indications (as posted on the analysis)
Posted indications: cuts, burns, chronic skin disease, frail children, chronic gynaecological complaints, diabetes, hypertension, arteriosclerosis, nervous complaints, muscle and joint pain, frozen shoulder, motor paralysis, stiffness, bruises, sprains, chronic digestive complaints, haemorrhoids, poor circulation, convalescence, fatigue, general health. Contraindications: sensitive skin or mucosa and photosensitivity, dry skin in the elderly, acute illness and others
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 |
|---|---|---|---|---|
| Zao Onsen (five source groups, 47 sources) | Unconfirmed | Unconfirmed | Unconfirmed | no check date |
| Great open-air bath source | 50.8 | 1.9 | Unconfirmed | no check date |
Three things not to miss
Three communal baths: Kami-yu, Shimo-yu, Kawarayu
In the town, around Takayu-dori street All three open 6:00–22:00 all year; you drop 300 yen (children 100) into a box, with no attendant. There is a footbath outside Shimo-yu. The association notes one bath where the water rises through the floorboards, a rarity in Japan.
Acid water for 300 yen from six in the morning; the baths locals use, open to anyone passing through.[1][3]
Zao Onsen Great Open-Air Bath
Up the valley above the town, beside the stream An outdoor bath in the forest along a mountain stream, fed straight from a 50.8°C source at about 735 litres a minute, pH 1.9. No showers. Adults 850 yen, children 400; weekdays 9:30–17:00, weekends to 18:00. In 2026 it opened on 25 April and closes from late November to mid-April; from June to early October there is also a night session (18:30–21:00, 1,000 yen).
The signage admits that the water is strong enough to eat away the floor and the rim of the pool.[2][1]
Ice monsters and skiing
Zao Ropeway and Zao Onsen ski area One of Japan's largest ski areas rises straight from the town, and on the upper slopes fir trees encased in rime and snow form the famous juhyo, or snow monsters. A snow-monster festival is held each winter.
Skiing followed by a 300-yen communal bath is simply how the day goes here.[3][4]
The story
Nineteen centuries of Takayu
Legend says the spring was found around AD 110 by Kibi no Tagayu, a follower of the hero Yamato Takeru on his eastern campaign, and that Tagayu became Takayu, "high bath". Known as Mogami-Takayu, it has had its Sukawa onsen shrine since ancient times. In the Edo period it thrived as the western trailhead for pilgrims to Zao Gongen, and an 1855 merchants' directory carries a map of the Mogami-Takayu baths.[1][3]
How Takayu became Zao
In 1950 a newspaper ran a national vote for the hundred best sights, and Yamagata residents flooded it with postcards for the Zao range, which topped the mountain category. Riding the excitement, Takayu renamed itself Zao Onsen, built up its highland resort facilities and expanded the ski area into one of Tohoku's great mountain resorts. In 2026, the association notes, Yamagata Prefecture was named in National Geographic's Best of the World list.[3][4]
Acid that eats the floor
Forty-seven sources give about 5,700 litres a minute, mostly around pH 1.6 and some as low as 1.25. The great open-air bath warns that the water itself corrodes the floor and the rim of the pool, and that, being free-flowing from the source, there are no showers. The three communal baths stand open and unstaffed from six in the morning to ten at night for 300 yen in a box. Water this acidic is simply the town's daily bath.[3][2][1]
Going solo
Easy for solo travellersUnconfirmed
Weekend / peak restrictionsUnconfirmed
Where to eat dinnerThe association's gourmet guide lists many restaurants. The local dish is karakara-jiru, a pork and taro soup spiked with sake lees and chilli
Private bathUnconfirmed
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.
Dec · Jan · Feb · Mar — Skiing and the snow monsters; Zao Juhyo festival. The great open-air bath is closed
Jun · Jul · Aug · Sep — Night sessions at the open-air bath (June to early October); the big Bon dance in August
Oct — Autumn colour and the ropeway autumn festival
Food, culture & experiences
Zao Ropeway and the snow monsters
Ride up from the town in winter to see the rime-coated firs on the summit slopes[4][3]
From the townKarakara-jiru
Pork and taro soup with sake lees and red chilli, created with a local restaurateur as Zao's signature dish[3]
Restaurants in townSukawa Onsen Shrine and Zao Daigongen
A shrine venerated in the town since ancient times; in the Edo period Zao was the western gateway for pilgrims to Zao Gongen[1][3]
In townZao Onsen Bon dance
Held on 9 August in 2026[4]
In townEditors' guide
Start the morning at the 300-yen communal baths, spend midday at the great open-air bath (late April to mid-November) and end with a bowl of karakara-jiru. In winter, ski or ride the ropeway to the snow monsters, then soak. The water is strongly acidic, so keep soaks short and rinse afterwards. Buses run from Yamagata Station, and in winter direct from Sendai.
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
Zaō Onsen (蔵王温泉) is a famous hot spring area on Mount Zaō in the northern part of Honshū, the main island of Japan.
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
- Bus journey time and frequency from Yamagata Station are unconfirmed
- Water-handling notices and tattoo policy at the three communal baths are unconfirmed
- The formal spring name, the 47 sources, the founding legend, the 1950 renaming and karakara-jiru are from Wikipedia (CC BY-SA); the association also tells the founding legend
- Single-guest policy at inns is unconfirmed
Sources
- 蔵王温泉とは(泉質・共同浴場・足湯・日帰り温泉施設) | 蔵王温泉観光協会蔵王温泉観光協会 · 2026-10-09
- 蔵王温泉大露天風呂 公式サイト蔵王温泉大露天風呂 · 2026-10-09
- 蔵王温泉 - Wikipedia(日本語版)Wikipedia · 2026-10-09
- 蔵王温泉マウンテン＆スノーリゾート | 蔵王温泉公式サイト(トップ)蔵王温泉観光協会 · 2026-10-09
Register sources
- 蔵王温泉 - Wikipedia(日本語版)Wikipedia · CC BY-SA 4.0 · 2026-10-09
- Wikidata Q7159554Wikidata · CC0 · 2026-10-09
Data status
Name & locationPublishedCoordinatesPublishedSpring typePublishedPhotosPublishedFacilitiesPublishedVisiting info (dated)PublishedEditorial articlePublished
Updated 2026-10-09
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