An electric power supply control device comprises a first converter, at least one second converter, and an electrical voltage control unit. The second converter can work in intermittent oscillation, and converts outputting electrical voltage from the first converter. The electrical voltage control unit controls the outputting electrical voltage of the first converter, so that the outputting electrical voltage is equal to or less than a minimum value of upper limits of operating electrical voltage of the second converter, and is more than or equal to a maximum value of lower limits of operating electrical voltage of the second converter, and at least one of the second converter performs low electric power behavior.