To provide a cleaning device capable of cleaning an air suction port of an air conditioner without scattering dust to the circumference, and thereby being suitably used in a place having a strict requirement for cleanliness such as a clean room of a factory, a hospital, a food-relevant facility, or the like.

The cleaning device 500 comprises internal space forming means 10 and 20 disposed adjacently to the air suction port to define an internal space, the internal space forming means including one or more access holes 30 and 40 allowing access to the inside from the outside of the internal space forming means, and the air in the internal space forming means flowing to the air suction port. Therefore, the dust generated in the internal space during cleaning of the air suction port is sucked to the air suction port without scattering to the outside.