Provided are a window cleaning apparatus and a method of controlling the same. The window cleaning apparatus including first and second cleaning units which are respectively attached on both surfaces of a window using a magnetic force to move together with each other includes a first magnetic module provided in the first cleaning unit, a second magnetic module provided in the second cleaning unit, a magnetic force detection part for detecting a magnetic force between the first and second magnetic modules, and a magnetic force control part for controlling the magnetic force between the first and second magnetic modules.