An objective of the invention is to obtain a cleaning unit which allows a cleaning mechanism, such as a dust removal device, for an air filter to be easily mounted in an indoor unit of an air conditioner that has an air filter on the intake side of an indoor fan. The cleaning unit includes: a chamber casing (101) connected to a room side of an indoor main unit (10) having an indoor heat exchanger (22) and an indoor fan (21) which draws air from the room and blows the air to the indoor heat exchanger (22); an air filter (30) provided in the chamber casing (101) on an intake side of the indoor fan (21); and a dust removal device (50) configured to remove dust captured by the air filter (30).