An outdoor unit for an air conditioner, comprising: a casing, including a portion defining an outlet through which air is discharged from the outdoor unit; an axial flow fan disposed in the casing for blowing air through the outlet, wherein the axial flow fan comprises: a hub; a plurality of main wings extending from the hub; and a rim connecting the main wings to one other and rotating integrally with the main wings; and one or more air entry blockers disposed at a clearance space between the rim and the portion of the casing defining the outlet, wherein the one or more air entry blockers include baffles (224,133) which restrict the flow of fluid in a certain path or redirect flow and are formed on at least one of the rim and the portion of the casing, wherein the rim comprises a curved portion with an inner diameter that progressively decreases in the flow direction of air forcibly blown by the main wings, characterised in that the baffles include: a plurality of first baffles on the casing portion and extending around the outlet; and a plurality of second baffles on and extending around the rim, wherein the second baffles are disposed between adjacent first baffles; the second baffles are formed at a lower height than the first baffles. a casing, including a portion defining an outlet through which air is discharged from the outdoor unit; an axial flow fan disposed in the casing for blowing air through the outlet, wherein the axial flow fan comprises: a hub; a plurality of main wings extending from the hub; and a rim connecting the main wings to one other and rotating integrally with the main wings; and one or more air entry blockers disposed at a clearance space between the rim and the portion of the casing defining the outlet, wherein the one or more air entry blockers include baffles (224,133) which restrict the flow of fluid in a certain path or redirect flow and are formed on at least one of the rim and the portion of the casing, wherein the rim comprises a curved portion with an inner diameter that progressively decreases in the flow direction of air forcibly blown by the main wings, characterised in that the baffles include: a plurality of first baffles on the casing portion and extending around the outlet; and a plurality of second baffles on and extending around the rim, wherein the second baffles are disposed between adjacent first baffles; the second baffles are formed at a lower height than the first baffles. a hub; a plurality of main wings extending from the hub; and a rim connecting the main wings to one other and rotating integrally with the main wings; and one or more air entry blockers disposed at a clearance space between the rim and the portion of the casing defining the outlet, wherein the one or more air entry blockers include baffles (224,133) which restrict the flow of fluid in a certain path or redirect flow and are formed on at least one of the rim and the portion of the casing, wherein the rim comprises a curved portion with an inner diameter that progressively decreases in the flow direction of air forcibly blown by the main wings, characterised in that the baffles include: a plurality of first baffles on the casing portion and extending around the outlet; and a plurality of second baffles on and extending around the rim, wherein the second baffles are disposed between adjacent first baffles; the second baffles are formed at a lower height than the first baffles. a plurality of first baffles on the casing portion and extending around the outlet; and a plurality of second baffles on and extending around the rim, wherein the second baffles are disposed between adjacent first baffles; the second baffles are formed at a lower height than the first baffles.