A brushless motor comprises a stator and a rotor rotatably mounted to the stator. The rotor comprises a shaft, a rotor core fixed onto the shaft and magnets fixed to the rotor core. Two covers are fitted to respective ends of the rotor core, with one of the covers covering one end of the rotor core and at least a part of the radially outer peripheral surface of the rotor core, while the other cover at least covering the other end of the rotor core. Preferably, the entire peripheral surface of the rotor core is substantially covered by the two covers and the gap between the two covers is sealed by adhesive.