An electric motor drive device includes a smoothing capacitor and an inverter, and further includes an overvoltage protection unit for overvoltage protection for the smoothing capacitor, and a phase short-circuit control unit. The overvoltage protection unit includes: a discharge circuit having a discharge resistor and an IGBT connected in series; and a first determination circuit which determines, with determination delay, that smoothing capacitor voltage exceeds first set voltage, and turns on the IGBT. The phase short-circuit control unit is provided in a control device for drive-controlling the inverter and includes a second determination circuit which determines, with a determination period longer than the determination delay of the first determination circuit, that smoothing capacitor voltage exceeds second set voltage lower than the first set voltage, to perform phase short-circuit control for the inverter.