Some fuel injection valve drive control devices for an internal combustion engine which use a voltage boosted from an in-vehicle battery to control driving of a fuel injection valve are provided with a discharge circuit for discharging electric charge accumulated in a boost capacitor in the event of an emergency. However, the discharge circuit is intended for emergency use and does not operate during normal control, resulting in a problem in that occurrences of failures could go unnoticed and undiagnosed. In order to solve the aforementioned problem, the present invention has a configuration provided with: a boost circuit which has a boost coil, a switching component (FFT or the like) for supplying a switching current from a battery source voltage to the boost coil, and a boost capacitor for accumulating a boosted voltage generated by the operation of the switching component; a discharge circuit for discharging the accumulated electric charge via a current limiting means (e.g. discharge resistor, constant current source) and a discharge switch (FET or the like); and a monitoring circuit for monitoring the accumulated voltage. The discharge circuit is caused to operate when the control device is shutting down and performs a deterioration/failure diagnosis of the boost capacitor and an operation check of the discharge circuit on the basis of a monitored voltage value of the boost capacitor at the time of starting the discharge operation and a monitored voltage value of the boost capacitor after a predetermined time has elapsed.