To reduce the number of parts used in a torque motor and to surely stop the rotor of the motor at an intermediate position, when the conduction to the coil section of the motor is turned off.

A rotor 41 is constituted of a rotor core 42 and permanent magnet groups 43 and 44 and spaces 49 elongated in the axial direction are formed between the magnet groups 43 and 44. The outer peripheries of the permanent magnets 43a and 44a are covered with a cover 48 made of a magnetic material. A slit 48a is formed through the cover 48 in the axial direction so that the position of the slit 48 in the peripheral direction may be shifted within the widths of the clearances 49. Since the magnetic fluxes concentrated to the vicinity of the slit 48a which works as a magnetoresistance section do not flow quickly but slowly to the tooth section of the stator core, the generating angle range of such torque that can rotate a throttle valve in the opening direction against the urging force of a return spring is wide. Therefore, the throttle valve can be held surely at an intermediate opening.