An indoor unit for an air conditioner including: a cabinet assembly forming an external appearance of the indoor unit and having a suction port formed in a rear surface of the cabinet; a filter module movably disposed in rear of the cabinet assembly; a filter module mounted to the filter mounting member and filtering foreign substances in air flowing into the suction port; a mobile member connected to the filter mounting member and moving a position of the filter mounting member; a driving device pressing the mobile member to change the position of the filter mounting member; and a controller configured to, in response to receiving a control command to change the position of the filter mounting member, operate the driving device that presses the mobile member.