PURPOSE: To improve energy efficiency by providing a thermoelectric generating element at a high temperature end, and driving a member to be cooled by a DC voltage generated at the element.

CONSTITUTION: A high temperature end 15 is engaged at its outer periphery with a cylindrical thermoelectric generating element 16. The element is formed of oxide, etc., to convert thermal energy to a DC electric energy by means of a Seebeck effect. The electric energy generated from the element 16 is effectively used to drive a member 17 to be cooled. The member 17 performs an excellent function by cooling it to a cryogenic temperature. More particularly, it is composed of an infrared ray sensor, an electromagnetic sensor, a high temperature superconducting element, etc. Compression heat of the end 15 of a pulse tube 14 is converted to DC electric energy by the element 16 by means of the Seebeck effect, and supplied to the member 17 to be cooled through leads.