To make it possible to cool a sample to an extremely low temperature without increasing the number of a heat conducting members, by providing contact thermal-resistance decreasing members between the heat conducting members of a pressure part.

Gold foils 10a and 10b, which are contact thermal-resistance reducing members, are provided between a copper foil 5a and a pressure contact member 5b, and gold foils 10e and 10h are provided between the copper foil 5a and a pressure contact member 5d. Furthermore, the gold foils 10b, 10c, 10f and 10g are provided between the copper foils 5a, respectively. The pressure contact members 5b and 5d are crushed, and a heat conducting body is formed. The gold foils 10a-10e are considerably soft in comparison with the copper foil 5a. Therefore, when the pressure contact members 5b and 5d formed of copper material are crushed, the gold foils 10a-10e enter the surface concave parts on both sides of the copper foil 5a and the surface concave parts of the copper foil 5a and the pressure contact members 5b and 5d and are brought into close contact with the concave parts. As a result, heat conduction at the pressure contact part becomes good, cold heat can be transmitted between heat conducting rods without increasing the number of the copper foils 5a, and samples can be cooled to a extremely cold temperature.