What to know
Shima Onsen (四万温泉, meaning "Forty-thousand Hot Spring") is a quiet hot spring town in the northwestern mountains of Gunma Prefecture. It ranks among the prefecture's top four hot spring destinations, along with Kusatsu, Minakami, and Ikaho, and is considered one of Japan's oldest. The name comes from the belief that bathing in its abundant waters could cure as many ailments as the number forty thousand suggests.
With over 40 hot spring sources, the town offers dozens of ryokan, public bathhouses, foot baths, and drinking fountains for visitors. Despite its many attractions, Shima has avoided overdevelopment, retaining a small-town feel. Nestled in a mountain valley, it boasts a beautiful natural backdrop of mountains, waterfalls, a reservoir lake, and a winding river. In autumn, the slopes offer stunning fall colors, typically peaking from late October to early November.
Shima Onsen stretches along the Shima River Valley and has three distinct areas, each about a kilometer apart. The lower town near the southern entrance is the quietest, home to some of the finest riverside ryokan. Here, the river forms a small but scenic gorge called Kamagafuchi Abyss.
The central area is the heart of Shima, where visitors stroll narrow streets lined with small shops, nostalgic game arcades, foot baths, and drinking fountains. Many ryokan and hotels are here, including the standout Sekizenkan, a centuries-old ryokan with a beautifully preserved Taisho Era Roman-style indoor bath.
The upper town is further into the valley and higher in elevation. Here you can bathe in the town's earliest discovered hot spring source at Gomusoyu public bath or visit nearby Yakushido Temple, dedicated to the town's founding. At the valley's end lies Okushima Lake, a reservoir formed by Shimagawa Dam, along with several waterfalls.
While the lower and central areas are walkable and close to each other, the upper area is more spread out and less pedestrian-friendly, especially around remote Okushima Lake. Buses run only to the Shima Onsen bus terminal in the central town. A rental car is recommended for exploring all areas at your own pace.