The present invention copes with fluctuations in a power supply voltage when a capacitor for coping with fluctuations in the power supply voltage has been omitted and also cases in which the power supply voltage is constantly low, thereby ensuring driving of an active element. A gate driving device of an IGBT includes: a first switch portion which turns on the IGBT; a second switch portion which turns off the IGBT; a current control portion which controls the outflow of charge on the gate to a ground line such that current is constant; a first protection circuit which suppresses outflow of gate current to the power supply line; and a second protection circuit which detects a prescribed fluctuation in an internal power supply voltage Vdc, and interrupts the connection between the current control portion and the ground line.