This three-phase AC motor drive device is provided with: a load; an inverter device 1 for driving the load; an MCOK_A_4 connected between the inverter device 1 and the load and electrically connecting or disconnecting the inverter device 1 to or from the load; a voltage detector 21a having terminals respectively connected to the circuits of at least two phases to detect the voltages between the three phases; and a current detector 11 for detecting the currents of the three phases. In the connection from the inverter device 1 to the load, the inverter device 1, the MCOK_A_4, the voltage detector 21a, the current detector 11, and the load are aligned in this order.