Japan Onsen Atlas温泉アトラス
Exterior of an old wooden long-stay inn
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Tohoku · Onsen area

Ōsawa Onsen

おおさわおんせん · 大沢温泉

Iwate · 花巻市

Open100 Onsen to Know Japan — No. 17
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Official classification

Spring type (therapeutic classes)

Simple hot spring

Official spring-type name (as recorded)Alkaline simple hot spring (hypotonic, alkaline, high-temperature)

Source temperature
51.3°C
pH
Unconfirmed
Flow rate
Unconfirmed
Radon
Unconfirmed

Appearance & feel

Water colour · Feel

Clear

Colour and feel are listed only where a source states them. They vary by day and by bath.

What makes it special

A mixed open-air bath hanging over the Toyosawa River, and a self-catering wing where a night costs a little over 4,000 yen. The old toji way of life is still intact here.
Why?

The inn's rate table for the Tojiya wing lists 4,080–5,630 yen for one person without meals, and describes the mixed outdoor bath Osawa-no-yu as sitting right against the Toyosawa River.[1][2]

Facilities in this area

Facilities come from the register (Wikipedia, OpenStreetMap, official sites). Those marked "natural spring unconfirmed" are listed on the basis of their name only.

Ryokan (inn) · Open

Osawa Onsen Tojiya (self-catering wing)

Day-use bathing
Yes
Fee
¥700checked 2026-10-09
Hours
日帰り 7:00–20:30受付(21:00終了)/宿泊者: 大沢の湯 5:00–24:00、薬師の湯 24時間(午前清掃あり)、かわべの湯 6:00–24:00checked 2026-10-09
Official site
Baths3
TypeGenderSourceBath temperatureFree-flowingAdded waterHeatedRecirculatedDisinfected
Open-air bathMixedOsawa OnsenUnconfirmedYes[4][2]Unconfirmed[4][2]Unconfirmed[4][2]No[4][2]Unconfirmed[4][2]
Open-air bathWomen onlyOsawa OnsenUnconfirmedYes[4][2]Unconfirmed[4][2]Unconfirmed[4][2]No[4][2]Unconfirmed[4][2]
Indoor bathSeparateOsawa OnsenUnconfirmedYes[4][2]Unconfirmed[4][2]Unconfirmed[4][2]No[4][2]Unconfirmed[4][2]
Ryokan (inn) · Open

Osawa Onsen Sansuikaku

Day-use bathing
Yes
Fee
¥700checked 2026-10-09
Hours
外来 7:00–20:30受付/宿泊者 豊沢の湯 24時間checked 2026-10-09
Official site
Baths2
TypeGenderSourceBath temperatureFree-flowingAdded waterHeatedRecirculatedDisinfected
Open-air bathSeparateOsawa OnsenUnconfirmedUnconfirmed[5]Unconfirmed[5]Unconfirmed[5]Unconfirmed[5]Unconfirmed[5]
Private bathUnconfirmedOsawa OnsenUnconfirmedYes[4][5]Unconfirmed[4][5]Unconfirmed[4][5]No[4][5]Unconfirmed[4][5]

Getting there

Reachable by public transport

From Hanamaki Station on the JR Tohoku Line, take the Iwate Kenko bus toward Shidotaira or Shin-Namari Onsen to the Osawa Onsen stop outside the inn; buses run once or twice an hour. Overnight guests can also use the Hanamaki-Minami onsen shuttle from Shin-Hanamaki and Hanamaki stations (15:10, 16:10, 17:10; a 100-yen contribution each way from September 2026). By car, 15 minutes from Hanamaki-Minami IC on Prefectural Road 12.

Getting there
Hanamaki Station (JR Tohoku Line) ·
Getting there
1–2 buses an hour from Hanamaki Station
Through the year
In winter Toyosawa-no-yu is glassed in and the women's Kawabe-no-yu may close in the coldest weeks; the Kikusuikan gallery shuts for winter
Checked
2026-10-09
Show on mapOpen in Google Maps

About the water

An alkaline simple hot spring at 51.3°C. The inn explains that simple means many minerals are dissolved but none dominates. Alkaline water is said to soften dead skin, and its gentleness suits the repeated daily bathing of a toji stay. The Tojiya's Osawa-no-yu, Yakushi-no-yu and Kawabe-no-yu, and Sansuikaku's private family baths, run straight from the source. The inn's posted advice, taken from the analysis sheet, is two or three baths a day, starting with three to ten minutes.

Indications (as posted on the analysis)

Posted indications (from the analysis sheet): neuralgia, muscle and joint pain, chronic digestive complaints, haemorrhoids, poor circulation, bruises, sprains, fatigue, general health. Contraindications: acute illness, serious heart disease, respiratory or kidney failure, severe anaemia, progressing disease, early or late pregnancy

Indications are an official statement based on the water analysis, not a guarantee of treatment. They are kept separate from opinions.

SourceSource temperaturepHRadonChecked
Osawa Onsen51.3UnconfirmedUnconfirmedno check date

Three things not to miss

A river running through a valley in fresh green leaf
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掬茶 CC BY-SA 4.0 View original page
01

Osawa-no-yu, the mixed open-air bath

Tojiya wing, on the Toyosawa River A mixed outdoor pool right above the river. Every evening 20:00–21:00 is women-only (suspended in the horsefly weeks of summer). No towels or swimwear in the water; it is lit after dark.

This is the bath where, the story goes, a young Kenji Miyazawa jammed the waterwheel that lifted the water and caused an uproar. A survivor from a less fussy age of bathing.[2][3][4]

Exterior of an old wooden long-stay inn
Photo information
掬茶 CC BY-SA 4.0 View original page
02

Tojiya, the self-catering wing

By the crooked bridge You pay the old way: a room rate, then add-ons such as quilt and mattress (220 yen each per day), yukata (220) or a heated table (330). The shared kitchen has coin-operated gas (10 yen for 7–8 minutes), and you can order cooked rice and miso soup. The Yahagi canteen serves set meals and buckwheat soba.

The longer you stay the cheaper it gets, and one person can settle in for weeks. The economics of Japanese toji, unchanged.[1][4]

An old building with a thatched roof
Photo information
掬茶 CC BY-SA 4.0 View original page
03

Three houses and the crooked bridge

Both banks of the Toyosawa River The modern Sansuikaku ryokan, the self-catering Tojiya and the thatched Kikusuikan are linked by a crooked wooden bridge. Kikusuikan now opens as the Chigaya gallery (closed in winter). The bridge appears in Eight Views of Osawa, painted by the late-Edo artist Kawaguchi Getsurei.

Pick a wing to suit your budget and mood; whichever you choose, you can wander between the baths.[3][5]

The story

Twelve centuries of hot water

Legend has the general Sakanoue no Tamuramaro, wounded by a poisoned arrow around 800 AD, healing quickly after bathing here. In 1867 the lord of the Nambu domain came for the cure and composed poems with his retainers, and the Eight Views of Osawa by the domain's painter Kawaguchi Getsurei still hang in the inn.[3]

Kenji and Kotaro

As a boy Kenji Miyazawa was brought here again and again by his devout father, since the inn hosted Buddhist lectures. As a student he stopped the waterwheel that lifted the bath water and threw the bathhouse into uproar; later, teaching at Hanamaki agricultural school, he brought his pupils to bathe. In 1945 the sculptor-poet Kotaro Takamura, his Tokyo studio burned, fled to Hanamaki on the strength of Kenji's father and stayed seven years, declaring that Osawa had the taste of a real hot spring.[3]

The inn that bills by the item

Tojiya still works the way cure spas always did: a bare room rate, then daily charges for whatever you borrow, so two yukata over three nights is 220 yen times two times three. Gas in the shared kitchen takes coins, and you can order rice from half a cup. For anyone wanting to linger, the inn suggests renting a room rather than paying for a day bath.[4][1]

Going solo

Easy for solo travellersYes
Weekend / peak restrictionsUnconfirmed
Where to eat dinnerThe Yahagi canteen (11:15–14:00 and 17:15–21:30) serves set meals, rice bowls and 100% buckwheat soba; you can also cook, and the shop sells groceries
Private bathNo

checked 2026-10-09

Through the year

Recommended months

JanFebMarAprMayJunJulAugSepOctNovDec

Months open

JanFebMarAprMayJunJulAugSepOctNovDec

"Recommended" and "open" are recorded separately. Check the season for seasonal springs.

May · Jun — Fresh green along the river; the glass doors of Toyosawa-no-yu open

Jul · Aug — During horsefly season the women-only hour at Osawa-no-yu is suspended

Oct · Nov — Autumn colour; the Chigaya gallery runs to early December (the 2026 special exhibition ends 6 Dec)

Dec · Jan · Feb · Mar — Snow bathing; heated tables and stoves are rented by the day

Food, culture & experiences

Available / bookable

Miyazawa Kenji Memorial Museum

Exhibits on the poet's thought and work in eight sections; the Fairy-tale Village, Ihatov Hall and city museum are nearby[3]

About 30 min by car from Osawa Onsen
Available / bookable

Takamura Kotaro's hut

The tiny hut where the sculptor-poet lived and cooked alone for seven years after fleeing to Hanamaki in 1945. He said Osawa tasted like a real hot spring[3]

About 10 min by car
Available / bookable

Chigaya gallery in the Kikusuikan

An exhibition space in the thatched former inn; a special show for Kenji Miyazawa's 130th birthday runs 18 Apr–6 Dec 2026[6]

Just over the crooked bridge

Editors' guide

Day visitors pay 700 yen at Tojiya and make the rounds: the mixed Osawa-no-yu, Yakushi-no-yu and Sansuikaku's Toyosawa-no-yu. Women can use the 20:00–21:00 hour or Kawabe-no-yu. To linger, rent a day room for 2,120 yen and eat soba at Yahagi. Better still, book a single room in Tojiya, hire a quilt and yukata, and cook for yourself for a few days; that is the real Osawa.

The "editors' guide" above is written by the editors from sources; it is not a visitor's opinion.

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Review posting is in preparation, with visit date, facility, comments on water, scenery and access, photos, language and reporting.

Onsen areas nearby

Unconfirmed & notes

  • Bus journey time from Hanamaki Station is unconfirmed (the timetable is an image)
  • pH, dilution and chlorination notices are unconfirmed, as are Sansuikaku's room rates and single-guest policy
  • The exact dates when the women-only hour is suspended are not stated

Register sources

Data status

Name & locationPublishedCoordinatesPublishedSpring typePublishedPhotosPublishedFacilitiesPublishedVisiting info (dated)PublishedEditorial articlePublished

Updated 2026-10-09

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