A semiconductor device includes a power semiconductor switching element, a comparator circuit, a filter circuit and an erroneous-detection prevention circuit. The comparator circuit compares a value of an output voltage of the switching element with a threshold and outputs a comparison result as a determination signal. The filter circuit outputs the determination signal to the control circuit after a delay time required for the output voltage of the switching element to reach a predetermined voltage value for determining that the switching element is in a normal ON state after the switching element is turned on. The erroneous-detection prevention circuit changes a turn-on time of the switching element, the delay time, or a voltage value of the determination signal when a voltage of the power supply drops in a case where the switching element is normally turned on.