PURPOSE: To obtain a semiconductor wafer heating device, which is superior in soaking property, has a small heat capacity and is good in temperature controllability, by a method wherein a fluid having a good thermal conductivity is sealed in the cavity of a heating stage having the cavity in its interior and this fluid is uniformly stirred.

CONSTITUTION: A semiconductor wafer is placed in the surface 2a of a heating stage 2A, the stage 2A has a cavity 13 in its interior and a fluid having a good thermal conductivity, such as mercury 14 which is a liquid metal, is sealed in the cavity 13. Moreover, a rotating propeller 15 is provided in the cavity 13 as a means for stirring forcedly and uniformly this mercury 14. The propeller 15 is rotated by a driving means provided outside of the stage 2A, such as a motor 16, and the mercury 14 is uniformly stirred. Thereby, even if the thickness of the stage 2A is not made thick, the surface temperature of the stage 2A can be made uniform and the stage 2A can be favorably subjected to temperature control.