A brushless motor includes a stator and a rotor. The stator includes an annular stator core having teeth arranged with a spacing in a circumferential direction of the annular stator core; and coils wound around the teeth respectively. The rotor includes a rotor core and magnetic poles of segment magnets arranged annularly along a circumferential direction of the rotor core. The segment magnets are stacked at a plurality of stages in an axial direction of the rotor core. A length direction of each of the segment magnets is parallel with the axial direction of the rotor core. The following expression is satisfied: (2×β/P)+θ