A drive device includes an off-side circuit controlling a gate current of a power switching element to perform an off operation. The off-side circuit includes: a main MOS transistor; a sense MOS transistor defining a drain current of the main MOS transistor; and a sense current control circuit controlling a drain current of the sense MOS transistor to be constant. The sense current control circuit includes: a reference power supply; a reference resistor; and an operational amplifier generating an output at the gate of the sense MOS transistor so that a potential between the reference resistor and the sense MOS transistor approaches the reference potential. The sense current control circuit flows a current, determined by a resistance value of the reference resistor and the reference potential, as the drain current of the sense MOS transistor.