PURPOSE: To miniaturize a snubber circuit and to enable removing the heat generated therefrom effectively by parallel-connecting the snubber circuit with a switching element for turning ON and OFF a current and by cooling the switching element and a selfextinction of arc-type semiconductor device through a common cooling means.

CONSTITUTION: A snubber circuit 10 is constituted by a power transistor 12, a high-speed diode 13 antiparallel-connected with the power transistor 12, a snubber capacitor 11 serially connected with these, and a base resistance 14 connecting the collector and base of the power transistor, and the snubber circuit 10 is parallel-connected with a switching element 4. When the switching element 4 being ON is turned OFF, the voltage V of the snubber capacitor 11 rises to discharge the stored charge of the snubber capacitor 11. The discharge current at that time is converted to heat so that the circuit is mounted on the same cooling fan as that of the power transistor 12.