To prevent slip dislocation of a wafer at the time of heat-treating the wafer, by constituting each of a plurality of substrate supporting sections in such an elastic supporting section that can independently move in the vertical direction.

A substrate supporting jig 2 is constituted in such a way that a plurality of coil springs 2a made of quartz glass are attached to the surface of an SiC annularly discoidal base 2b, so that the springs 2a may elastically support a wafer 1 placed on the supporting points 2c of the jig 2 provided at the upper ends of the springs 2a. In addition, the coil springs 2a are constituted in such a way that, when the wafer 1 is deformed, the supporting points 2c independently move to the positions corresponding to the deformation of the wafer 1 in the vertical direction by the elastic deformation of the springs 2a. Therefore, the occurrence of the slipping dislocation of the wafer 1 can be prevented at the time of heat-treating the wafer 1.