To provide a thermotreatment method and an instrument to be used for the same with which thermotreatment at the desired part of a human body to perform the thermotreatment can be easily, usefully and inexpensively performed anywhere without limiting operation.

While using a material to generate heat by air oxidization and a material to radiate far infrared rays as materials for effectively providing the thermotreatment operation, the thermotreatment for the body is performed by heat generated by the air oxidization of the material to generate the heat by the air oxidization and the far infrared rays radiated from the material to radiate the far infrared rays and when the thermotreatment is not performed, the material to generate heat by air oxidization is preserved while being shielded from external air so as not to perform the air oxidization of the material to generate heat by air oxidization.