# Zao Onsen Dairotenburo

> Zao Onsen's seasonal outdoor bath, fed straight from a strongly acidic sulfur spring. ¥850 for adults, open from late April to November.

- Prefecture: Yamagata
- Type: Onsen
- Address: Yamagata, Japan
- Opening hours: Mon–Fri 09:30–17:00 / Sat–Sun 09:30–18:00
- Closed: Open every day in season, apart from the odd maintenance day. Closed in winter, from its November closing day until late April.
- Hours note: 9:30 to 17:00 on weekdays (last entry 16:30) and 9:30 to 18:00 on weekends and holidays (last entry 17:30). The 2026 season opened on 25 April; the closing date in November had not been announced. The bath also shuts on the odd maintenance day.
- Admission: 850 yen
- Official site: http://www.jupeer-zao.com/roten/
- Hours and fees checked against the official site: 2026-11-05

The Dairotenburo is Zao Onsen's big outdoor bath, about 18 minutes on foot from the bus terminal. The water is the same strongly acidic sulfur spring as the rest of the town, pH 1.9 here. It comes out of the ground at 50.8 degrees, about 735 litres a minute, and runs into the baths without being recirculated. The bath is open only from late April to November and closes for the winter. Soap and shampoo cannot be used, so this is a bath for soaking, not for washing. The acid turns silver and gold black, so take off rings, earrings and necklaces before you get in. Towels are on sale and there are coin lockers. In autumn 2026 it also opened in the evening on set dates in September and October. The town's three communal baths are open all year.

## FAQ

### When is the Zao Onsen Dairotenburo open?

From late April to November, every day: 9:30 to 17:00 on weekdays and 9:30 to 18:00 on weekends and holidays, with last entry 30 minutes before closing. It is closed all winter. In winter, use the communal baths Kamiyu, Shimoyu or Kawarayu, open 6:00 to 22:00 all year.

### What should I know before bathing at the Dairotenburo?

Soap and shampoo cannot be used, and the acidic water turns gold and silver black, so remove all jewellery first. Towels are sold on site and there are coin lockers. Do not drink the water.

---
Source: [Zao Onsen Dairotenburo — Japan Voyage](https://travel.japanvoyage.jp/travel_destinations/zao-onsen-dairotenburo)
Last updated: 2026-11-05