To provide a heating treatment device capable of effectively heating only a lesion site while preventing damage to normal tissues around the lesion site by presuming a temperature and a position corresponding to each other inside viable tissues during heating treatment.

A presumption part 12 presumes a distance from the surface of a surface layer 21 to the point of a highest temperature in the viable tissues and the highest temperature by utilizing a relational expression stored in a memory 9 based on the input information of a surface layer temperature and a deep part temperature before the heating treatment, elapsed time after irradiation start and the surface layer temperature and the deep part temperature at present obtained by a surface layer temperature sensor 14 and a deep part temperature sensor 15, etc. The presumed values are displayed on a monitor 7. An operator confirms that set treatment conditions are not erroneous during the heating treatment by referring to the predicted values displayed on the monitor 7 and the irradiation insufficiency and excessive irradiation of laser beams are prevented.