Disclosed is a thermotherapy in which a thermal gas such as hot vapor which is warm vapor is inhaled through a mouth or a nose, and the inhaled thermal gas spreads to every alveolus of lungs. Due to such a thermotherapy, the whole respiratory organ is warmed and, at the same time, heat energy is applied to blood through the alveoli of the lungs so that human body tissues are easily warmed within a short time by transferring the heat energy to whole parts of a human body by making use of the circulation of blood. Accordingly, not only a healthy person but also a patient can easily enjoy advantageous effects of a thermotherapy which is equal to or higher than advantageous effects of a sauna or hot spring.
