PURPOSE: To cool or heat an external heat medium by a method wherein a thermoelectric transducer in which the two ends of a thermoelectric material are brought into contact with two heat sources having different temperatures and the two ends are connected to each other with an electrode to apply a current to the thermoelectric material with its own thermoelectromotive force is provided and a heat exchange means by which heat is exchanged between the thermoelectric transducer and an external heat medium is provided in a part of the thermoelectric transducer.

CONSTITUTION: The two ends of a thermoelectric material 1 are connected to each other with an electrode 5 and the two ends are brought into contact with a high temperature heat source 10 and a low temperature heat source 11 respectively. At that time, a thermoelectromotive force is generated in the thermoelectric material 1 and a current is applied to the thermoelectric material 1 through the electrode 5 to produce heat absorption or heat generation by a Thomson effect. A pipe 21 through which heat medium 20 flows is brought into contact with a part of a thermoelectric transducer to exchange heat between the transducer and the heat medium 20. With this constitution, the heat medium 20 can be cooled or heated without a current supplied from an external electrode.