A brushless synchronous motor includes a stator having a plurality of phase coils, a rotor disposed opposite the stator, a magnetic sensor for detecting a rotation angle of the rotor, a power supply circuit connected to the phase coils, a control circuit for controlling the power supply circuit so that the motor rotates synchronously. In the above motor, a circuit board includes a wiring circuit connecting the phase coils with the power supply circuit, and the magnetic sensor is directly fixed to the circuit board so that dimensional variation of the magnetic sensor relative to the stator can be minimized.