An electronic control apparatus controls am electrically-driven vehicle, which has no engine but has only a motor supplied with electric power from an electric power supply source. The electronic control apparatus has a self-diagnosis function for storing an abnormality code corresponding to a diagnosis object when abnormality of the diagnosis object is detected. The electronic control apparatus checks whether the motor and the electric power supply source are operating normally when a power control switch is turned on under a state that the abnormality code is stored in a memory. The electronic control apparatus checks whether abnormality is detected again in the diagnosis object, the abnormality code of which has already been stored, when the motor and the electric power supply source are operating normally. The electronic control unit erases the abnormality code when no abnormality is detected again.