To provide components of a high temperature, high pressure device capable of preventing loose fastening of a device in which two or more of parts are fastened by bolts and also preventing damage of a screw portion of the bolts while the device is used in a high temperature and high pressure state.

In the components of the high temperature, high pressure device forming a female screw 12 in a first parts 2 as an object to be fastened and also bolt-fastening and bolt-fixing both parts by means of a bolt 13 screwed with the female screw and also passing through a second parts 2, an end portion 101 of the first parts 1 in the proximity of the second parts 2 is formed by material having superior strength at high temperature, and an other end portion 102 of the first parts is formed by material having a superior thermal conductive property. Thus, these two materials are connected together to provide the first parts 1. The components have sufficient strength and tenacity to required performance during operation and can expect longer life. Because of integral compound material, combination of necessary construction material can be easily changed in proportion to conditions for temperature and projecting pressure against specification change of operating conditions of the device and material of products.