PROBLEM TO BE SOLVED: To efficiently absorb hydrogen into a human body.SOLUTION: There is provided the hydrogen carbonic acid bath which generates hydrogen carbonic acid water in which a dissolution density of hydrogen is 0.2 ppm or greater and 1.2 ppm or smaller, a dissolution density of carbon dioxide is 250 ppm or greater and 3000 ppm or smaller, using a mixed gas of hydrogen and carbon dioxide, and the hydrogen carbonic acid water is supplied continuously to a bathtub 13. In the bathtub 13, a user stays for 10 minutes or longer at once bathing, thereby performing cutaneous absorption of hydrogen.SELECTED DRAWING: Figure 1COPYRIGHT: (C)2020,JPO&INPIT【課題】水素を人体内に無理なく、効果的に吸収できるようにする。【解決手段】水素の溶存濃度が0.2ppm以上1.2ppm以下であり、二酸化炭素の溶存濃度が250ppm以上3000ppm以下である水素炭酸水を、水素と二酸化炭素の混合ガスを溶かして生成するとともに、水素炭酸水を浴槽13に対して連続して供給できる水素炭酸風呂。その浴槽13内に、1回の入浴につき10分以上滞在させることによって、水素を経皮吸収させる。【選択図】図1