Provided is a ground fault detection device including a detection capacitor, a positive electrode power supply side resistor, a negative electrode power supply side resistor, a positive electrode ground side resistor, a negative electrode ground side resistor, a positive electrode side twin relay selectively switching a connection point of one end of the detection capacitor; a negative electrode side twin relay selectively switching a connection point of the another end of the detection capacitor, and a controller controlling switching of the positive electrode side twin relay and the negative electrode side twin relay, and calculating an insulation resistance of the system provided with the high-voltage battery based on a charging voltage of the detection capacitor, and determines there is a possibility that a sticking fault has occurred.