The official figures (as of March 2025)
Every year the Ministry of the Environment compiles reports from the prefectures into the "Onsen Usage Survey". The national figures for FY2024 (as of 31 March 2025) are:
- Onsen areas: 2,839
- Spring sources: 27,899 (used and unused)
- Flow: about 2.4 million litres per minute
- Lodgings using onsen water: 13,425
- Public baths using onsen water (day-use): 7,721
- Overnight guest-nights per year: about 120 million
Sixty years earlier, in FY1962, there were 1,518 onsen areas and 13,079 sources. Sources have more than doubled, largely because deep drilling now brings up hot water even in cities.
"Onsen areas" counts only places with lodging
The ministry's "onsen area" means a place that has at least one lodging using onsen water. Places with only day-use baths, hamlets with only a communal bathhouse, and wild springs are not counted. So it covers a different set from the areas this atlas collects by name, which include day-use-only places and historic springs.
The 2,839 is also a sum of prefectural reports, and prefectures draw the boundaries of "one area" differently — is Beppu's "eight baths" one area or eight?
You cannot add them up into a "total"
Areas, sources, lodgings and public baths each count something different. One onsen area may hold dozens of sources and hundreds of inns; one source may be shared by several facilities. Adding them together to claim "Japan has X tens of thousands of onsen" is a mistake.
This atlas records areas, facilities, baths and sources as separate layers, and on each prefecture page and in the national register it shows the official statistics beside the number of places it has confirmed by name. Our counts are coverage figures, not the total number of hot springs in Japan.
Which prefectures have the most?
Hokkaido has the most onsen areas (226), followed by Nagano (193), Niigata (135), Fukushima (122) and Aomori (120). By number of sources, Oita (about 4,400) and Kagoshima (about 2,700) stand far ahead, then Shizuoka (2,185) and Hokkaido (2,249). For lodgings the order is Shizuoka, Nagano, Hokkaido.
The prefecture map lets you switch between the official statistics and this atlas's coverage.
663highland · CC BY 2.5
Calistemon · CC BY-SA 4.0
Noboribetsu Onsen
登別温泉
Hokkaido · 100 Onsen to Know Japan — No. 1
Ten thousand tonnes of water a day and nine kinds of spring, all boiling out of a single valley called Hell.
663highland · CC BY-SA 4.0
Atami Onsen
熱海温泉
Shizuoka · 100 Onsen to Know Japan — No. 56
More than 500 sources give about 20,000 litres a minute at an average of 63 °C; from the foot bath outside the station to the geyser up the hill, the whole town is built on hot water.
Glossary
- Spring source (gensen)
- One outlet where onsen water emerges or is pumped. "Self-flowing" sources rise naturally; "powered" sources are pumped.
- Guest-nights
- Total overnight stays; one person staying two nights counts as two.
Related onsen
663highland · CC BY 2.5
Calistemon · CC BY-SA 4.0
Noboribetsu Onsen
登別温泉
Hokkaido · 100 Onsen to Know Japan — No. 1
Ten thousand tonnes of water a day and nine kinds of spring, all boiling out of a single valley called Hell.