The invention relates to a motor comprising a base, a bearing, a positioning piece, a rotor and a stator. The base is provided with a shaft tube; the bearing is arranged in the shaft tube and provided with a through hole and a concave part having an axial direction; the positioning piece is combined with the bearing, provided with a perforation and a plurality of grooves and has a radial direction from the inner hole wall of the perforation to the inner hole wall of the through hole of the bearing, wherein the radial direction is no more than the axial direction; the rotor is provided with a rotating shaft which is combined with the through hole of the bearing; and the stator is sleeved on the outer peripheral surface of the bearing. Accordingly, the invention can utilize the concave part of the bearing to provide the positioning piece with an enough deformation space, thereby facilitating the assembly operation of the rotor and the positioning piece and effectively preventing the positioning piece from being damaged in the assembly process.