This paper proposes to paste non-magnetic materials on the rotor surface of a cylindrical brushless DC motor and to use the model including the extended e.m.f. for sensorless control. In the proposed method, the inductance changes depending on the rotor position because of eddy currents, which flow on the non-magnetic material at high frequency. The rotor position can be estimated at standstill and at low speeds. The simulation results show that the proposed method is very useful.