A fan comprises a stator base, a rotor, at least one blade, an upper magnetic pole plate, a lower magnetic pole plate, a coil and a sidewall. The stator base comprises a stator base having a seat and a tubular portion protruding from the seat and having an axial hole. The seat and the tubular portion are formed as a monolithic piece to be a magnetic conductor. The rotor enclosing the tubular portion comprises a shaft disposed in the axial hole. The blades are circumferentially disposed at a periphery of the rotor. The upper magnetic pole plate is disposed near a top of the tubular portion and the lower magnetic pole plate is disposed near a bottom of the tubular portion. The coil is disposed between the upper and lower magnetic pole plates. The sidewall is circumferentially disposed at a periphery of the stator base.