The upper block 12 contacts the bearing block 20, and the bearing block 20 is coupled to the upper plate 21. The upper block 12 has a protruding part 22 on the upper surface that is worked into a convex surface with a radius of R1, and the bearing block 20 has a recessed part 23 in the undersurface that is worked into a concave surface with a radius of R2 (R2>R1). As a result of such a construction being used, the pressing surface of the upper pressing plate 15 always conforms to the surface of the quartz crystal substrate 11 during pressing, so that a uniform load is applied to the quartz crystal substrate 11. As a result, the surface of the quartz crystal can be uniformly pressed in the hot pressing method.