A steering assist apparatus, comprising: an assist actuator for generating performance for assisting a steering force of a steering wheel; a vehicle-mounted battery for supplying electric power to the assist actuator; an alternator for charging the vehicle-mounted battery; a steering state detection unit for detecting a steering state of the steering wheel; a vehicle speed detection unit for detecting a vehicle speed of a vehicle; a reverse stage detection unit for detecting that a transmission of the vehicle has been shifted to a reverse stage, and a voltage control unit for controlling an output voltage of the alternator based on detection information of each of the steering state detection unit and the vehicle speed detection unit, wherein the voltage control unit controls the output voltage of the alternator, when a stopping state of the vehicle is detected based on the detection information of the vehicle speed detection unit, in response to the steering state of the steering wheel detected by the steering state detection unit before the vehicle stops; and authorizes control for increasing the output voltage of the alternator when it is detected based on the detection information of the vehicle speed detection unit that the vehicle is running at a predetermined vehicle speed or lower, and when it is detected by the steering state detection unit that the steering wheel has been steered in a predetermined state, characterized in that when it is detected by the reverse stage detection unit that shifting to the reverse stage has been performed, the voltage control unit controls the output voltage of the alternator such that the output voltage of the alternator is increased. an assist actuator for generating performance for assisting a steering force of a steering wheel; a vehicle-mounted battery for supplying electric power to the assist actuator; an alternator for charging the vehicle-mounted battery; a steering state detection unit for detecting a steering state of the steering wheel; a vehicle speed detection unit for detecting a vehicle speed of a vehicle; a reverse stage detection unit for detecting that a transmission of the vehicle has been shifted to a reverse stage, and a voltage control unit for controlling an output voltage of the alternator based on detection information of each of the steering state detection unit and the vehicle speed detection unit, wherein the voltage control unit controls the output voltage of the alternator, when a stopping state of the vehicle is detected based on the detection information of the vehicle speed detection unit, in response to the steering state of the steering wheel detected by the steering state detection unit before the vehicle stops; and authorizes control for increasing the output voltage of the alternator when it is detected based on the detection information of the vehicle speed detection unit that the vehicle is running at a predetermined vehicle speed or lower, and when it is detected by the steering state detection unit that the steering wheel has been steered in a predetermined state, characterized in that when it is detected by the reverse stage detection unit that shifting to the reverse stage has been performed, the voltage control unit controls the output voltage of the alternator such that the output voltage of the alternator is increased. controls the output voltage of the alternator, when a stopping state of the vehicle is detected based on the detection information of the vehicle speed detection unit, in response to the steering state of the steering wheel detected by the steering state detection unit before the vehicle stops; and authorizes control for increasing the output voltage of the alternator when it is detected based on the detection information of the vehicle speed detection unit that the vehicle is running at a predetermined vehicle speed or lower, and when it is detected by the steering state detection unit that the steering wheel has been steered in a predetermined state, characterized in that when it is detected by the reverse stage detection unit that shifting to the reverse stage has been performed, the voltage control unit controls the output voltage of the alternator such that the output voltage of the alternator is increased.