In a semiconductor device in the related art, it has been necessary to match the threshold voltage of a power element with the circuit operation of a gate driver; accordingly, it has been difficult to realize the operation of the gate driver most appropriate for the employed power element. According to one embodiment, when a power element is turned off, the semiconductor device monitors the collector voltage of the power element, and increases the number of NMOS transistors that draw out charges from the gate of the power element in a period until the collector voltage becomes lower than the pre-set determination threshold, rather than in the period after the collector voltage becomes lower than the determination threshold.