A window cleaning robot according to the present embodiment comprises a first cleaning unit and a second cleaning unit, which are respectively attached to and move on both surfaces of a window by magnetic force. The window cleaning robot further comprises: a first magnetic module included in the first cleaning unit; a second magnetic module included in the second cleaning unit; a magnetic force sensing part for sensing magnetic force between the first magnetic module and the second magnetic module; and a magnetic force controller for controlling the magnetic force between the first magnetic module and the second magnetic module, wherein the first magnetic module comprises a first magnet which is rotationally mounted, and a second magnet and a third magnet disposed on both sides of the first magnet, and the magnetic force controller rotates the first magnet so as to control the magnetic force between the first magnetic module and the second magnetic module.