A drive circuit Dr for a switch that reduces a surge voltage caused when a switch SW is switched to an off state. The drive circuit Dr detects, as an on voltage Von, a collector-emitter voltage of the switch SW while the switch SW is in an on state. When the detected on voltage Von is large, the drive circuit Dr sets a resistance value Rd of a discharging resistor 53 when the switch SW is switched to an off state to be larger than the resistance value Rd when the detected on voltage Von is small. More specifically, the drive circuit Dr sets the resistance value Rd to a larger value as the detected on voltage Von is increased.