hot spring headimage


Since the Edo period, this onsen has been gushing out of the ground,The three most beautiful onsen for skin.Onsen containing everything overflow today. Souce-of-onsen free-flowing Gongen-no-yu.


The only one selected as a national recreational onsen resort in Kanagawa Prefecture Ashinoyu Onsen.Hot springs with excellent effects on the skin, etc.

The color of the spring water is unusual in that it is emerald green at first and turns cloudy white depending on the temperature. The onsen gushes out at a rate of 200 liters per minute and is completely free-flowing. The famous onsen that has been praised since the Edo period is available,
and You can still enjoy the same. A variety of drinks, including alcohol, are available in the lounge, free of charge.

hot springの紹介

Onsen Composition

All of the three major qualities of onsen for beautiful skin: sulfur spring, sulfate spring, and bicarbonate spring are Contains.

Our onsen water is a "sulfur spring" that is expected to remove sebum and dirt, and to promote blood circulation and metabolism.

Sulfate spring is expected to coat the skin, restore elasticity, moisturize, and be effective for arteriosclerosis, trauma, and itchy skin.

It is a rare onsen that contains all three major qualities for beautiful skin: a "bicarbonate spring" that dissolves sebum and makes skin smooth and beautiful like soap, and a "bicarbonate spring" that is expected to be effective against skin diseases.

The mildly alkaline nature of the spring water makes it soft to the touch and prevents irritation.

  • Onsen qualitySulfur containing - calcium, sodium, magnesium - sulfate, hydrogen carbonate spring (hydrogen sulfide type) (former name: Sodium bicarbonate - gypsum hydrogen sulfide spring), slightly alkaline, hypotonic, high temperature spring
  • efficacy Beauty skin, helps heal neuralgia, rheumatism, skin diseases, etc.
  • Onsen Information 100% free-flowing Onsen water
    Gushing volume: approx. 300,000 L/day (approx. 200-250 L/minute) = approx. 1,500 bathtubs/day

How to take onsen

History of Onsen

The onsen in Ashinoyu is "Gongen-no-yu"

The history of the Hakone Ashinoyu onsen is long, dating back to the Nara period (710-794), more than 1,260 years ago.As the onsen of Ashinoyu is "Gongen-no-yu," the general public is not allowed to enter Ashinoyu, and of course, bathing and other activities are not permitted.In addition, the Gongen is said to have originated when it was used by court nobles, priests, and ascetics who made pilgrimages to the shrine.

Gongen: Hakone Sansho Gongen (now Hakone Shrine), built by Manmaki Shonin

Onsen resort for national recreation

The Ministry of the Environment (MOE) has designated these onsen resorts as suitable for mental and physical recuperation, recreation, and rest since 1954, based on Article 29 of the onsen law. As of October 2019, there are 80 designated sites throughout Japan.
Ashinoyu Onsen was designated as a National Recreational Onsen Resort in 2015.

The conditions specified are broadly divided into those related to the source and those related to the onsen resort.

  • Objective.Mental and physical recuperation, recreation, and rest
  • At the source.Terms and Conditions The source must be a therapeutic spring with high efficacy. Gushing rate must be 0.5L/minute or more per onsen user. The temperature of the onsen must be at least 25 degrees Celsius.
  • To the onsen resortTerms and Conditions Surrounding landscape blessed with natural environment Environment as a recreational area, history, climate, culture Medical facilities and staff using onsen. Transportation, and Safety against disaster. * Onsen resorts with entertainment districts are excluded in terms of recreational areas, etc.

Large public bath

Year 2023 Newly renovated large public baths.

free-flowing hot spring waterWe do not heat, add water, or circulate water.

Hot springs and our employees

As of June 1, 2020, two hot spring bathing instructors are on staff at the hotel. In addition, in order for our guests to enjoy "Onsen" and "Travel" even more, we have also developed the following features to make your stay more enjoyable:
More qualified personnel related to hot springs. More areas of expertise about health and spring quality related to hot springs, as well as bathing techniques to help you improve.
Study sessions are held on a regular basis.

  • bathroom Men's and women's large public baths 1 each
  • Hours of Use Check-in from 0:00am / 5:00am - 9:30am
  • Bathroom Supplies Body soap / Shampoo / Conditioner / Cleansing gel / Lotion / Milky lotion / Shower cap

Private open-air bath

In April 2019, five private baths will be Newly opened. Free of charge for guests.

Our onsen is 100% free-flowing and enjoys the rich effects of our own hot spring water, which bubbles up from its own source.Families and couples can enjoy a blissful time of healing both body and soul in a relaxed atmosphere without worrying about being seen.

  • Hours of Use 3:00pm-11:45pm / 7:00am-9:45am ( 1 time 45 min. )
  • How to use Reservations can be made at the front desk after check-in.
  • Bathroom Supplies Body soap/shampoo/conditioner/dryer/face & hand wash

free-flowing hot spring waterWe do not heat, add water, or circulate water.

Private room source for private use Open-air day-trip bathing

Play with the colors and scents of the season. A room with a spacious sofa and an open-air bath with a view of the forest and soaking in nature's song. And a lounge break is available as a set.This is a new proposal for a standing spa.

Room charge: 8,800 yen / 1 or 2 persons Includes ◎drinks and bath towel. You do not need to bring anything with you.

Day trip bathing