An air conditioner, comprising: a main body; a centrifugal blower provided in the main body; a heat exchanger provided in the main body, surrounding the centrifugal blower; and an inlet/outlet panel assembly movably coupled to the main body, and dividing an inside of the main body into a suction region and an exhaust region, the inlet/outlet panel assembly having an air inlet that guides air into the main body, wherein the centrifugal blower comprises: a motor; a centrifugal fan rotatably coupled to the motor, wherein the centrifugal fan comprises: a hub fixed to a rotary shaft of the motor; a main plate provided at an outer circumferential surface of the hub; a shroud positioned upstream of the main plate, opposite the main plate, and having a suction opening formed therein surrounding the rotary shaft; and a plurality of wings arranged circumferentially with respect to the suction opening, between the main plate and the shroud; and a bell mouth guiding air into the centrifugal fan, wherein the bell mouth comprises: a rear portion inserted into the shroud through the suction opening such that the rear portion forms a predetermined radial gap with the suction opening, characterized in that the bell mouth further comprises: a plurality of protrusions formed at a rear end of the rear portion; and a plurality of recesses respectively formed between the plurality of protrusions, wherein the plurality of protrusions and the plurality of recesses are inserted into the shroud. a main body; a centrifugal blower provided in the main body; a heat exchanger provided in the main body, surrounding the centrifugal blower; and an inlet/outlet panel assembly movably coupled to the main body, and dividing an inside of the main body into a suction region and an exhaust region, the inlet/outlet panel assembly having an air inlet that guides air into the main body, wherein the centrifugal blower comprises: a motor; a centrifugal fan rotatably coupled to the motor, wherein the centrifugal fan comprises: a hub fixed to a rotary shaft of the motor; a main plate provided at an outer circumferential surface of the hub; a shroud positioned upstream of the main plate, opposite the main plate, and having a suction opening formed therein surrounding the rotary shaft; and a plurality of wings arranged circumferentially with respect to the suction opening, between the main plate and the shroud; and a bell mouth guiding air into the centrifugal fan, a motor; a centrifugal fan rotatably coupled to the motor, wherein the centrifugal fan comprises: a hub fixed to a rotary shaft of the motor; a main plate provided at an outer circumferential surface of the hub; a shroud positioned upstream of the main plate, opposite the main plate, and having a suction opening formed therein surrounding the rotary shaft; and a plurality of wings arranged circumferentially with respect to the suction opening, between the main plate and the shroud; and a hub fixed to a rotary shaft of the motor; a main plate provided at an outer circumferential surface of the hub; a shroud positioned upstream of the main plate, opposite the main plate, and having a suction opening formed therein surrounding the rotary shaft; and a plurality of wings arranged circumferentially with respect to the suction opening, between the main plate and the shroud; and a bell mouth guiding air into the centrifugal fan, wherein the bell mouth comprises: a rear portion inserted into the shroud through the suction opening such that the rear portion forms a predetermined radial gap with the suction opening, characterized in that the bell mouth further comprises: a plurality of protrusions formed at a rear end of the rear portion; and a plurality of recesses respectively formed between the plurality of protrusions, wherein the plurality of protrusions and the plurality of recesses are inserted into the shroud. a plurality of protrusions formed at a rear end of the rear portion; and a plurality of recesses respectively formed between the plurality of protrusions, wherein the plurality of protrusions and the plurality of recesses are inserted into the shroud.