An outer sliding sunroof apparatus having a roof panel attached to an opening of a fixed roof of a vehicle, a drive device for opening and closing the roof panel, and a control unit for controlling the drive device. The apparatus further includes a load detector for detecting load applied to the drive device when the roof panel in a closed state is tilted up and moved toward a rear of the vehicle. When the load detector detects the load not less than a predetermined amount of load, the control unit is configured to move the roof panel in the closing direction.