Yamagata · Zao Onsen
Zao Onsen Dai-Rotenburo
蔵王温泉大露天風呂
A terraced open-air bath along a mountain stream that holds 200 people, with bluish-white strongly acidic sulfur water. Open late April to late November only; closed in winter. Summer starlight sessions at night.
- Price (adult)
- ¥1,000
- Hours
- weekdays 09:30–17:00 / Sat/Sun/hol 09:30–18:00(late Apr–late Nov)
- Closed
- Closed in winter(late Nov–late Apr)
- Access
- 20 min walk from Zao Onsen bus terminal
- Water type
- Acidic spring
- Tattoos
- Ask ahead
- Phone
- 023-694-9417
- Official site
- www.jupeer-zao.com/roten ↗
- Open in Google Maps
- Google Maps ↗
Essentials
Stay in this onsen town
Compare and book stays in Zao Onsen. Day bathing itself needs no booking.
Opens partner booking site (affiliate)
Why go
- Terraced tubs jutting into the gorge
- Extremely acidic sulfur water (pH ~1)
- Summer-only night-time bathing
Before you go
- No official tattoo policy is published — ask at reception.
- Strongly acidic water — rinse off afterwards, avoid long soaks, and remove silver jewellery.
- Open seasonally only — check the official site for operating dates before you go.
- Last entry is 30–60 minutes before closing.
Features
Mood & scenery
Convenience
Price
Amenities
✔ Verified operating: 2026-09 やまがた観光情報 2025-12 (大人1,000円)
Prices and hours change. Check official sources before visiting.
More in this area
Shirogane-yu (Ginzan communal bath)
A Kengo Kuma-designed communal bath at the entrance to Ginzan's Taishō-era street. Hot water with drifting mineral flakes for ¥500. The one place day visitors can bathe in Ginzan's water — reception closes at 3:30 pm.
Zao Onsen Kamiyu Public Bath
A log-cabin-style communal bath at the top of Takayu-dōri. Zao's three public baths (Kamiyu, Shimoyu, Kawarayu) all cost ¥200, paid into an honesty box. No washing stations — just rinse and sink into the strongly acidic milky sulfur water.
Ginzan Onsen Ginzansō (Day Bath)
The large ryokan at the entrance to Ginzan. Indoor, open-air and lie-down outdoor baths — far roomier than Shirogane-yu. Day use 11:30 am–2 pm (last 1:30), ¥1,500, closed Thursdays; day bathing has been suspended and resumed repeatedly, so check the website. Cash only.