A rear lamp unit control system for a vehicle including: a first lamp provided on a vehicle body side of a vehicle rear face; a second lamp provided on an opening-closing body side of the vehicle rear face; and a controller configured to control the first lamp and the second lamp. When an opening-closing body of the vehicle is in a closed state, the controller is configured to control the first lamp and the second lamp so that the first lamp and the second lamp turn on at different luminous intensities to each other. In response to the second lamp being in need to be turned on when the opening-closing body is in an open state, the controller is configured to turn the first lamp on at a luminous intensity that is equivalent to a luminous intensity of the second lamp when the second lamp is turned on.