To provide a motor control device capable of maintaining a reverse connection prevention transistor in an on state during an application time period of a surge voltage while achieving a more compact and low-cost configuration.

In a motor control device ECU in which a control circuit 18 receives a power from a battery B via a motor drive circuit MC to control rotation of the motor M, a reverse connection prevention transistor 303 preventing a current from being flown in the motor drive circuit MC when the battery B is reverse-connected, a power supply instantaneous interruption prevention capacitor 10 discharged when supply of power from the battery B to the control circuit 18 is instantaneously interrupted, and a power supply sneak prevention diode 402 arranged between the power supply instantaneous interruption prevention capacitor 10 and a gate terminal of the reverse connection prevention transistor 303, are arranged in the motor drive circuit MC. When a high-voltage negative surge voltage is applied to an anode of the battery B, a current flows from the power supply instantaneous interruption prevention capacitor 10 to the gate terminal of the reverse connection prevention transistor 303.