MOTOR DRIVE DEVICE

A motor drive device (100) includes: an inverter circuit (11); a drive circuit (9) which receives a voltage supplied from a control power source(1); a first cutoff circuit (3) which cuts off voltage supply from the control power source (1) to the drive circuit (9); a second cutoff circuit (13) which is connected between the first cutoff circuit (3) and the drive circuit (9); a voltage detection circuit (30) which detects a detection voltage corresponding to the voltage supplied from the control power source (1) and which is capable of changing the detection voltage; a comparison circuit (21) which, upon determination that the detection voltage is not within a predetermined range, cuts off the first cutoff circuit (3); and a diagnosis circuit (14) which diagnoses the first cutoff circuit (3), wherein the diagnosis circuit (14) causes the comparison circuit (21) to cut off the first cutoff circuit (3), performs diagnosis operation of diagnosing the first cutoff circuit (3), and upon diagnosing operation of the first cutoff circuit (3) as being abnormal, cuts off the second cutoff circuit (13).