A gate drive circuit includes a power supply circuit (11) that has an output switch function for switching a voltage value of a drive voltage (VOM) between two levels, a gate-ON drive circuit (12) that outputs a constant electric current (Ia) toward a gate of an IGBT (6) from an output terminal (Po) of the power supply circuit (11), and a control section (4) performs a constant electric current drive of a gate of the IGBT (6) at a time of a turn-ON by operating the gate-ON drive circuit (12). At a turn-ON start time, the control section (4) sets the drive voltage (VOM) to a relatively-high first set value, and then switches the drive voltage to a relatively-low second set value (VOM2) at a switch timing after a mirror period end time.