The present invention discloses an air conditioner including a heat exchanger for exchanging heat with the air, an air suction hole (301) for sucking the air, a filter for filtering off dust passing through the air suction hole (301), and a cleaning unit moved along the filter, for removing the dust from the filter by using a suction force, the cleaning unit including a chamber having a first opening portion for sucking the dust and a second opening portion for discharging the dust.