日本は約3,000以上もの温泉地があり、源泉総数は28,000ヶ所以上存在します。
温泉地、源泉数ともに世界一となります。様々な種類や成分の温泉があり、日本列島の地熱活動が活発である事から、この多様性が生まれています。
◆主要な温泉の種類◆
日本が世界に誇る温泉文化。単に温まるだけでなく、温泉にはそれぞれ異なる「泉質」があり、それが温泉の持つ個性や期待できる効能につながっています。泉質を知ることで、その日の体調や気分にぴったりの温泉を選ぶ楽しみが生まれます。
今回は、代表的な泉質の種類と、それぞれの泉質で知られる有名な温泉地をご紹介します！
1. 単純温泉（単純泉）
- どんなお湯？ 温泉成分の量が比較的少なく、肌への刺激が少ない優しいお湯です。ほとんどが無色透明で、においもあまりありません。pH7.5以上のアルカリ性単純温泉が多いですが、中性や弱酸性のものもあります。
- 期待される効能： リラクゼーション効果が高く、万人におすすめできるお湯です。疲労回復や健康増進に良いとされています。
- 有名な温泉地：
- 下呂温泉 (岐阜県)
- 由布院温泉 (大分県)
- 道後温泉 (愛媛県)
- 伊香保温泉 (群馬県)
- 鬼怒川温泉 (栃木県) など
2. 硫黄泉
- どんなお湯？ 硫黄成分を含んでおり、特徴的なゆで卵のようなにおいがします。白濁したり、エメラルドグリーンに変色したりと、見た目にも個性的です。
- 期待される効能： 「湯の花」としても知られる成分で、特に皮膚病や関節炎、慢性婦人病などに良いとされます。解毒作用や殺菌作用も期待できます。
- 有名な温泉地：
- 草津温泉 (群馬県)
- 登別温泉 (北海道)
- 蔵王温泉 (山形県)
- 酸ヶ湯温泉 (青森県)
- 万座温泉 (群馬県)
- 玉川温泉 (秋田県) など
3. 塩泉
- どんなお湯？ 塩分を多く含む温泉です。入浴すると塩分が肌に膜を作り、汗の蒸発を防ぐため体が芯から温まりやすく、湯冷めしにくいのが特徴です。
- 期待される効能： 保温効果が高く、「熱の湯」とも呼ばれます。リラックス効果や保湿効果も期待できます。主に海に近い地域で多く見られます。
- 有名な温泉地：
- 登別温泉 (北海道)
- 黒川温泉 (熊本県)
- 玉造温泉 (島根県)
- 鳴子温泉 (宮城県)
- 熱海温泉 (静岡県) など
4. 鉄泉
- どんなお湯？ 鉄分を多く含んだ温泉です。湧き出したばかりは無色透明でも、空気に触れると酸化して赤褐色に変色することが多いです。「赤湯」と呼ばれることもあります。金気臭が特徴です。
- 期待される効能： 鉄分には血行促進効果があるとされ、筋肉痛や関節痛、冷え性などに良いとされています。「子宝の湯」として知られることもあります。
- 有名な温泉地：
- 有馬温泉 (兵庫県) – 金泉が有名
- 登別温泉 (北海道)
- 鳴子温泉 (宮城県)
- 玉川温泉 (秋田県)
- 天草温泉 (熊本県) など
5. ラジウム泉
- どんなお湯？ 微量のラジウム（ラドン）を含有する温泉です。吸入や飲用、入浴によって体内に取り込まれたラドンが、微量の放射線（アルファ線）を出すことで体の細胞を刺激し、活性化させると言われています。
- 期待される効能： リウマチや神経痛、痛風、高血圧症などに良いとされ、「万病の湯」と呼ばれることもあります。
- 有名な温泉地：
- 三朝温泉 (鳥取県)
- 増富温泉 (山梨県)
- 村杉温泉 (新潟県) など
6. 炭酸泉
- どんなお湯？ 炭酸ガス（二酸化炭素）を多く含む温泉です。お湯に浸かると肌に炭酸の小さな泡が付着することがあります。湯温が低いほど炭酸ガスが多く溶け込みます。
- 期待される効能： 炭酸ガスが皮膚から吸収されると血管が拡張し、血行促進効果が非常に高いのが特徴です。疲労回復やリフレッシュ、高血圧の方にも良いとされます。
- 有名な温泉地：
- 長湯温泉 (大分県)
- 有馬温泉 (兵庫県) – 銀泉に含まれます
- 初谷温泉 (長野県)
- 花山温泉 (和歌山県) など
7. 放射能泉
- どんなお湯？ 温泉水中にラドンやトロンといった放射性物質を一定量以上含む温泉の総称です。ラジウム泉は放射能泉の一種です。
- 期待される効能： 微量の放射線による細胞活性化効果が期待され、痛風、リウマチ、神経痛などに良いとされます。
- 有名な温泉地：
- 三朝温泉 (鳥取県)
- 湯の山温泉 (三重県)
- るり渓高原温泉 (京都府) など（ラジウム泉と重なる温泉地が多いです）
8. 酸性泉
- どんなお湯？ pH値が4.5以下の酸性度が高い温泉です。肌に浸透しやすく、殺菌力が強いのが特徴です。ピリッとした肌触りを感じることがあります。
- 期待される効能： 強力な殺菌作用から、皮膚病やアレルギー症状の緩和に良いとされています。肌が弱い方は注意が必要です。
- 有名な温泉地：
- 草津温泉 (群馬県)
- 玉川温泉 (秋田県)
- 登別温泉 (北海道)
- 蔵王温泉 (山形県)
- 酸ヶ湯温泉 (青森県) など
9. アルカリ泉
- どんなお湯？ pH値が高いアルカリ性の温泉です。肌の古い角質を取り除くピーリング効果が期待でき、肌がつるつる、ぬるぬるした感触になることから「美肌の湯」として非常に人気があります。
- 期待される効能： 肌をなめらかにする美容効果の他、リラックス効果や疲労回復にも良いとされています。
- 有名な温泉地：
- 白馬八方温泉 (長野県)
- 七沢温泉郷 (神奈川県)
- 中山平温泉 (宮城県)
- 嬉野温泉 (佐賀県) など
10. 塩化物泉
- どんなお湯？ 温泉水中に塩化物イオンを多く含む温泉です。塩分が肌に付着して汗の蒸発を防ぎ、入浴後の保温効果が高いのが特徴です。「食塩泉」とも呼ばれます。
- 期待される効能： 体が温まりやすく、湯冷めしにくいことから、冷え性や筋肉痛、関節痛、神経痛などに良いとされています。
- 有名な温泉地：
- 有馬温泉 (兵庫県)
- 別府温泉 (大分県)
- 登別温泉 (北海道)
- 黒川温泉 (熊本県)
- 城崎温泉 (兵庫県)
- 和倉温泉 (石川県)
- 指宿温泉 (鹿児島県) など
いかがでしたか？ 一口に「温泉」と言っても、これだけ多様な泉質があり、それぞれに魅力的な温泉地が存在します。
今回ご紹介した以外にも、様々な特徴を持つ温泉はたくさんあります。ぜひ、色々な泉質を巡って、あなただけのお気に入りの「推し湯」を見つけてみてくださいね！
Get More Enjoyment! A Guide to Japan’s Major Onsen Water Types and Famous Locations
Japan has over 3,000 onsen areas and more than 28,000 spring sources, making it number one in the world for both. This diversity of types and components is born from the active geothermal activity of the Japanese archipelago.
Japan boasts a proud onsen culture that is world-renowned. More than just warming the body, each hot spring (onsen) has a different “water quality” (泉質, senshitsu), which gives it unique characteristics and expected effects. Knowing the water quality adds to the pleasure of choosing the perfect onsen for your physical condition and mood that day.
In this article, we will introduce the major types of onsen water and famous onsen locations known for each quality! Find your preferred water type and use it as a reference for your next onsen trip.
◆ Major Types of Onsen Water ◆
1. Simple Onsen (Tanjun-sen)
- What kind of water? This type of onsen has a relatively low concentration of hot spring components, making it gentle on the skin with little irritation. Most are colorless, transparent, and have hardly any odor. Many are alkaline simple onsen with a pH of 7.5 or higher, but some are neutral or slightly acidic. They are characterized by being easy for anyone to enter, from babies to the elderly.
- Expected effects: Highly effective for relaxation and recommended for everyone. It is said to be good for relieving fatigue and promoting health. The skin often feels smooth after bathing.
- Famous onsen locations:
- Gero Onsen (Gifu Prefecture)
- Yufuin Onsen (Oita Prefecture)
- Dogo Onsen (Ehime Prefecture)
- Ikaho Onsen (Gunma Prefecture)
- Kinugawa Onsen (Tochigi Prefecture) etc.
2. Sulfur Onsen (Iou-sen)
- What kind of water? This onsen contains sulfur components and has a characteristic rotten egg smell. It is a prime example of “cloudy water” (nigori-yu), and is visually unique, appearing milky white or even changing to emerald green. The pH can range from strongly acidic to alkaline.
- Expected effects: Known for its “onsen flowers” (yu no hana), it is said to be particularly good for skin diseases, joint pain, and chronic gynecological conditions. Detoxification and bactericidal effects can also be expected. Its strong scent enhances the feeling of being at an onsen!
- Famous onsen locations:
- Kusatsu Onsen (Gunma Prefecture) – famous for strong acidity
- Noboribetsu Onsen (Hokkaido)
- Zao Onsen (Yamagata Prefecture)
- Sukayu Onsen (Aomori Prefecture)
- Manza Onsen (Gunma Prefecture)
- Tamagawa Onsen (Akita Prefecture) – strongly acidic etc.
3. Salt Onsen (Shio-sen)
- What kind of water? This onsen contains a high concentration of salt. When you bathe, the salt creates a film on your skin, preventing sweat evaporation. This makes the body warm up thoroughly and retain heat, so you feel warm long after getting out of the bath. It often tastes salty.
- Expected effects: Highly effective for warming the body and is also called “hot water” (netsu no yu). Recommended for people who feel cold easily. Relaxation effects and skin-tightening effects from the salt can also be expected. It is often found in areas close to the sea.
- Famous onsen locations:
- Noboribetsu Onsen (Hokkaido)
- Kurokawa Onsen (Kumamoto Prefecture)
- Tamatsukuri Onsen (Shimane Prefecture)
- Naruko Onsen (Miyagi Prefecture)
- Atami Onsen (Shizuoka Prefecture) etc.
4. Iron Onsen (Tetsu-sen)
- What kind of water? This onsen contains a high concentration of iron. While it is colorless and transparent when it springs up, it often oxidizes when exposed to air and turns reddish-brown. It is sometimes called “red water” (aka-yu). It has a characteristic metallic (kanake) smell. Be careful as towels and other items may get stained.
- Expected effects: Iron is said to promote blood circulation, making it good for muscle pain, joint pain, cold sensitivity, and chronic gynecological conditions. It is sometimes known as a “fertility bath” (kodakara no yu). Some locations have drinking springs that are said to be good for anemia.
- Famous onsen locations:
- Arima Onsen (Hyogo Prefecture) – Kinsen (Gold Spring) is famous
- Noboribetsu Onsen (Hokkaido)
- Naruko Onsen (Miyagi Prefecture)
- Tamagawa Onsen (Akita Prefecture)
- Amakusa Onsen (熊本県) etc.
5. Radium Onsen (Rajiumu-sen)
- What kind of water? This onsen contains small amounts of radium (radon). It is said that radon taken into the body by inhalation, drinking, or bathing emits a small amount of radiation (alpha rays), which stimulates and activates the body’s cells. The water itself is often gentle with little irritation.
- Expected effects: It is said to be good for conditions such as rheumatism, neuralgia, gout, and high blood pressure, and is sometimes called the “onsen of a thousand ailments” (manbyou no yu). It is popular as a place for therapeutic bathing (Touji).
- Famous onsen locations:
- Misasa Onsen (Tottori Prefecture) – drinking spring is also famous
- Masutomi Onsen (Yamanashi Prefecture)
- Murakami Onsen (Niigata Prefecture) etc.
6. Carbon Dioxide Onsen (Tansan-sen)
- What kind of water? This onsen contains a high concentration of carbon dioxide gas. When you soak in the water, tiny carbon dioxide bubbles may adhere to your skin. More carbon dioxide dissolves in water at lower temperatures (around body temperature or lower), so natural high-concentration carbon dioxide springs are rare.
- Expected effects: Carbon dioxide absorbed through the skin expands blood vessels, resulting in a very high blood circulation promotion effect. It is particularly good for relieving fatigue, refreshing the body, and is said to be beneficial for people with high blood pressure. Since it puts less strain on the heart, it is also called “heart water” (shinzou no yu).
- Famous onsen locations:
- Nagayu Onsen (Oita Prefecture)
- Arima Onsen (Hyogo Prefecture) – included in the Ginsen (Silver Spring)
- Shotou Onsen (長野県)
- Hanayama Onsen (和歌山県) etc.
7. Radioactive Onsen (Houshanou-sen)
- What kind of water? This is a general term for onsen water that contains a certain amount of radioactive substances such as radon or thorium. Radium onsen is a type of radioactive onsen. It is recognized as a therapeutic onsen based on scientific evidence.
- Expected effects: Cell activation effects from trace amounts of radiation are expected, and it is said to be good for conditions such as gout, rheumatism, neuralgia, high blood pressure, and diabetes. Recommended for when you want to refresh your body from within.
- Famous onsen locations:
- Misasa Onsen (Tottori Prefecture)
- Yunoyama Onsen (Mie Prefecture)
- Rurikei Kogen Onsen (Kyoto Prefecture) etc. (Many onsen locations overlap with Radium Onsen)
8. Acidic Onsen (Sansei-sen)
- What kind of water? This onsen has high acidity with a pH value of 4.5 or lower. It penetrates the skin easily and has strong bactericidal properties. When you bathe, you may feel a slightly tingling or tightening sensation on your skin. In locations with high concentrations of components, the type of bathtub material may be limited.
- Expected effects: Due to its strong bactericidal effect, it is said to be good for relieving skin diseases like athlete’s foot and allergy symptoms. However, caution is needed for those with sensitive skin or when taking long baths.
- Famous onsen locations:
- Kusatsu Onsen (Gunma Prefecture)
- Tamagawa Onsen (Akita Prefecture)
- Noboribetsu Onsen (Hokkaido)
- Zao Onsen (Yamagata Prefecture)
- Sukayu Onsen (Aomori Prefecture) etc.
9. Alkaline Onsen (Arumikari-sen)
- What kind of water? This onsen has a high alkaline pH value. Especially those with a pH of 8.5 or higher are expected to have a peeling effect that removes old skin cells and dirt. Because they make the skin feel smooth and slippery, they are very popular as “beauty skin baths” (bihada no yu). Many are colorless, transparent, and have little odor.
- Expected effects: Their beauty effects, which make the skin smooth, are the most notable. In addition, they are also said to be good for relaxation and relieving fatigue. Many people feel their skin is moisturized after bathing.
- Famous onsen locations:
- Hakuba Happo Onsen (長野県) – famous for strong alkalinity
- Nanasawa Onsenkyo (神奈川県)
- Nakayamadaira Onsen (宮城県)
- Ureshino Onsen (佐賀県) – One of Japan’s Three Great Beauty Skin Onsen etc.
10. Chloride Onsen (Enkabutsu-sen)
- What kind of water? This onsen contains a high concentration of chloride ions. The salt adheres to the skin, preventing sweat evaporation and significantly increasing the body’s heat retention after bathing. It is also called “table salt onsen” (shokuen-sen) and tastes salty.
- Expected effects: As it warms the body easily and makes it difficult to cool down, it is said to be good for cold sensitivity, muscle pain, joint pain, and neuralgia. It is also said to be beneficial for dry skin.
- Famous onsen locations:
- Arima Onsen (Hyogo Prefecture)
- Beppu Onsen (Oita Prefecture)
- Noboribetsu Onsen (Hokkaido)
- Kurokawa Onsen (Kumamoto Prefecture)
- Kinosaki Onsen (Hyogo Prefecture)
- Wakura Onsen (Ishikawa Prefecture)
- Ibusuki Onsen (Kagoshima Prefecture) etc.
How was it? Even just saying “onsen,” there are such diverse water types, and each has its own charming onsen locations.
Besides the ones introduced here, there are many other onsen with various characteristics, and some onsen towns even have spring sources with multiple water types.
By all means, learn about the individuality and effects of each water type, and try visiting various onsen locations. You are sure to find your own favorite “oshi-yu” (favorite hot spring) to recommend!
コメントを残す