To obtain a highly reliable electronic control device capable of reliably causing a microcomputer to perform normal termination and normal re-activation by controlling a power supply voltage. According to the present invention, an electronic control device 25 includes a microcomputer 18, a power supply control unit 20 that controls a power supply voltage of the microcomputer, and a capacitor 19 provided between the power supply control unit and the microcomputer. The power supply control unit 20 includes a power supply unit 24 that supplies a first power supply voltage V1 to the microcomputer by turning ON an activation signal for activating the microcomputer, and stops the supply of the power supply voltage by turning the activation signal OFF, a reset control unit 14 that generates a Low reset signal by turning the activation signal OFF, and a discharge control unit 12 that discharges electric charges of the capacitor when acquiring the Low reset signal.