A variable rail-driven surface cleaning robot device is disclosed. The variable rail-driven surface cleaning robot device of the present invention comprises: a main body moving along rail members provided on an object to be cleaned including solar panels; a driving means provided at the main body to move the main body along the rail members; a cleaning means which is provided at the main body to clean the surface of the object to be cleaned and which has a rotary brush that is connected to the driving means and rotates; a rail-gap-correcting part provided at the main body to correct the gap of the rail members in correspondence to the gap between the plurality of rail members; and a rail-height-correcting part provided at the main body to correct the height of the main body in correspondence to the height of the plurality of rail members.