A fan drive circuit 1 for a heat pump device is provided. The heat pump device blows air heat exchanged by a heat exchanger using a mildly-flammable or flammable refrigerant having a specific gravity greater than that of air from a blowout port using a fan. The fan drive circuit 1 is equipped with a forced operation circuit configured to operate the fan in the event that it is undetectable that a protection device for preventing a leaked refrigerant from the heat pump device from reaching a combustible density is connected to the heat pump device.