A semiconductor switch drive device (3) includes a drive unit (10), a power supply unit (20), a switch (39), and a control unit (50). The drive unit (10) supplies a control signal to a semiconductor switch (Q) of a main circuit (2) and drives the semiconductor switch (Q). The power supply unit (20) supplies electric power to the drive unit (10). The switch (39) cuts off supply of electric power to the power supply unit (20) by detecting or controlling an overvoltage state on a primary side of the power supply unit (20). The control unit (50) switches a conductive state of the switch (39) on the basis of a voltage of a control terminal of the semiconductor switch (Q).