To prevent the temperature of an IC package from exceeding a standard temperature for a short circuit test, by setting the heat generation detecting temperature of a second heat generation detecting means which detects the temperature of an IC chip in a motor driving circuit reaching a second heat generation detecting temperature lower than the first one, to a value lower than the standard temperature for a short circuit test.

A first heat generation detecting circuit 3 detects the temperature of an IC chip in a motor driving circuit 1 reaching a first heat generation detecting temperature, and a second heat generation detecting circuit 4 detects the temperature of the IC chip in the motor driving circuit 1 reaching a second heat generation detecting temperature, and the second heat generation detecting temperature is set lower at least than the first heat generation detecting temperature. A drive interrupting circuit 5 performs control so as to interrupt the operation of the motor driving circuit 1, when the temperature of the IC chip reaches the first heat generation detecting temperature set by the first heat generation detecting circuit 3. Here, the second heat generation detecting temperature set by the second heat generation detecting circuit 4 is set to a value lower than the standard temperature of a short circuit test.