An indoor unit comprising: a chassis installed on a ceiling; an air inlet section configured to take in air and provided on a lower panel of the chassis; an air filter configured to collect dust in the air taken in and detachably attached to the air inlet section; a cleaning unit movable along a surface on the air inlet side of the air filter, the cleaning unit including: a dust-removing unit configured to remove dust collected on the air filter; and a collecting unit configured to temporarily store the dust removed from the air filter; the dust-removing unit includes a rotary brush having a rotary shaft rotating around the central axial line and a brush unit extending in the radial direction of the rotary shaft, and the collecting unit covers the rotary brush and has an opening where the rotary brush contacts the air filter, and characterized by: a driving unit configured to generate a driving force for moving the cleaning unit; a reciprocating unit driven in a reciprocating manner by the driving unit; a first transmitting unit configured to receive the driving force from the reciprocating unit; and a second transmitting unit configured to transmit the driving force from the first transmitting unit to the cleaning unit, wherein the driving unit, the reciprocating unit, and the first transmitting unit are disposed on the chassis, and the cleaning unit and the second transmitting unit are disposed on the air filter, and the first transmitting unit and the second transmitting unit are capable of engaging and disengaging. a chassis installed on a ceiling; an air inlet section configured to take in air and provided on a lower panel of the chassis; an air filter configured to collect dust in the air taken in and detachably attached to the air inlet section; a cleaning unit movable along a surface on the air inlet side of the air filter, the cleaning unit including: a dust-removing unit configured to remove dust collected on the air filter; and a collecting unit configured to temporarily store the dust removed from the air filter; the dust-removing unit includes a rotary brush having a rotary shaft rotating around the central axial line and a brush unit extending in the radial direction of the rotary shaft, and the collecting unit covers the rotary brush and has an opening where the rotary brush contacts the air filter, and characterized by: a driving unit configured to generate a driving force for moving the cleaning unit; a reciprocating unit driven in a reciprocating manner by the driving unit; a first transmitting unit configured to receive the driving force from the reciprocating unit; and a second transmitting unit configured to transmit the driving force from the first transmitting unit to the cleaning unit, wherein the driving unit, the reciprocating unit, and the first transmitting unit are disposed on the chassis, and the cleaning unit and the second transmitting unit are disposed on the air filter, and the first transmitting unit and the second transmitting unit are capable of engaging and disengaging. a dust-removing unit configured to remove dust collected on the air filter; and a collecting unit configured to temporarily store the dust removed from the air filter; the dust-removing unit includes a rotary brush having a rotary shaft rotating around the central axial line and a brush unit extending in the radial direction of the rotary shaft, and the collecting unit covers the rotary brush and has an opening where the rotary brush contacts the air filter, and characterized by: a driving unit configured to generate a driving force for moving the cleaning unit; a reciprocating unit driven in a reciprocating manner by the driving unit; a first transmitting unit configured to receive the driving force from the reciprocating unit; and a second transmitting unit configured to transmit the driving force from the first transmitting unit to the cleaning unit, wherein the driving unit, the reciprocating unit, and the first transmitting unit are disposed on the chassis, and the cleaning unit and the second transmitting unit are disposed on the air filter, and the first transmitting unit and the second transmitting unit are capable of engaging and disengaging. a driving unit configured to generate a driving force for moving the cleaning unit; a reciprocating unit driven in a reciprocating manner by the driving unit; a first transmitting unit configured to receive the driving force from the reciprocating unit; and a second transmitting unit configured to transmit the driving force from the first transmitting unit to the cleaning unit, wherein the driving unit, the reciprocating unit, and the first transmitting unit are disposed on the chassis, and the cleaning unit and the second transmitting unit are disposed on the air filter, and the first transmitting unit and the second transmitting unit are capable of engaging and disengaging.