The indoor unit of an air conditioner (1) comprising a filter (3), a cleaning unit (4) for cleaning the filter (3), a filter driving section (42) for moving the filter (3) in a dedicated direction and an open panel (15), for opening and closing the intake grill (14) in front of the casing, wherein the open panel is opened during filter cleaning and the filter is extruded to the outside of the casing of the indoor unit (1) along an inner surface of the open panel (15).