The present patent application concerns an apparatus for cleaning an outer surface of a rotor blade of a wind turbine, the apparatus comprising a first frame and a cleaning device, the cleaning device being adapted to conform to the outer surface and connected to the first frame, wherein the apparatus is adapted to be slidably positioned on the outer surface of the rotor blade, to slide along, and to be pressed onto the outer surface. Further, it concerns an apparatus for cleaning a leading edge of a rotor blade of a wind turbine, the apparatus comprising a first frame and a cleaning device, the cleaning device being adapted to conform to the leading edge and being connected to the first frame, wherein the apparatus is adapted to be slidably positioned on the leading edge of the rotor blade, to slide along and to be pressed onto the leading edge during standstill of a wind rotor comprising the rotor blade. Finally, it concerns a rotor blade of a wind turbine comprising an apparatus for cleaning a leading edge of the rotor blade, wherein the apparatus is mounted on said rotor blade, the apparatus comprising a first frame and a cleaning device, the cleaning device being adapted to conform to the leading edge and being attached to the first frame, wherein the apparatus is adapted to be slidably positioned on the leading edge of the rotor blade, to slide along and to be pressed onto the leading edge during rotation of a wind rotor comprising the rotor blade.