An external rotor motor includes an inner stator and an external rotor. The external rotor includes a casing and a plurality of magnets. The casing has an annular inner wall. The annular inner wall faces the inner stator and surrounds the inner stator. The magnets are placed along the annular inner wall of the casing. The magnets surround the inner stator. An end of at least one of the magnets has a round edge, a curvature radius of the round edge is R, a thickness of the at least one of the plurality of magnets is T, and the following condition is satisfied: 0.85≤R/T≤1.