A fan includes a base, a motor and an impeller, and the motor includes a sleeve, a rotor, a position limiting element and a composite elastic element. The sleeve is disposed on the base, and the sleeve has a bottom portion and a side wall, which constitute an accommodation space. The rotor has a rotating shaft disposed within the accommodation space, and the rotating shaft has an outer wall. An annular groove is formed on the outer wall and has a surface. The position limiting element is disposed on the sleeve and extended from the side wall toward the rotating shaft, and the position limiting element has a bottom surface. The bottom surface faces toward the bottom portion, and the bottom surface is interfered with the surface, thereby eliminating the gap between the bottom surface and the surface. Therefore, noise of the up and down vibration is avoided from generating.