Zao Onsen, Yamagata City, Yamagata Prefecture
Zao Onsen Dairotenburo
Come for the stream, forest and strongly acidic sulfur spring, not for a full-service bathhouse. It suits a scenic day visit if you can wash beforehand; anyone who needs showers or soap should choose another facility.
Facility photos
Check before bathing
- Opening hours
- On weekdays, 09:30–17:00 with last admission at 16:30. Weekends and public holidays: 09:30–18:00, last admission 17:30. Seasonal winter closure applies. On 7 September 2026, maintenance moved last admission to 15:30 and closing time to 16:00.
- Tattoo policy
- The current first-party pages reviewed do not confirm a tattoo policy. Check with the bath before visiting.
Spring & water temperature
- Spring-source temperature
- 50.8°C at the source; this is not the fixed temperature of the open-air pools.
- Bathing temperature
- Not published as a fixed temperature.
- Spring source
- The spring used by Zao Onsen Dairotenburo; the current main pages do not publish a specific well name.
- Spring classification
- Strongly acidic sulfur spring, as described by the facility.
- pH
- pH 1.9.
- Flow rate
- About 735 L/min for the facility's spring; this is not the flow allocated to any one pool.
- Water handling
- Zao Onsen Kanko says the bath uses source-flowing water. The current main pages do not publish full pool-by-pool details for water addition, heating, circulation or disinfection, so no further conditions are inferred.
Bathing indications
The facility lists general bathing indications including cuts, burns, chronic skin conditions, neuralgia, muscle and joint pain, sensitivity to cold and fatigue. These are not treatment guarantees.
Source-flowing use is confirmed; other pool treatment conditions are not published.
Admission is ¥850 for adults and ¥400 for children aged one to under 12. There are no showers, and soap and shampoo cannot be used. The strongly acidic water can affect eyes, jewellery and clothing. Tattoo rules are unconfirmed.
How to read a bath profile
Spring-source temperature and actual bathing temperature are kept separate. Each score is shown independently for comparison rather than collapsed into one overall score.
