To solve the problem that, when a conventional resolver which uses the transformer principle is used for rotational position detection in a brushless motor, adjustment of mechanical phase angle between a rotational shaft of the motor and a rotor side winding of the resolver to a constant value is required, resulting in increases in costs in manufacturing many motors.

There is provided a position detecting device in a brushless motor, in which position detection signals for carrying out rectification are obtained directly from main magnetic poles of drive magnets by using a plurality of hall elements. These position detection signals from the hall elements are a plurality of sinusoidal waves from which information on rotational position in the motor is obtained. Since magnetic fluxes of the drive magnets fixed to the rotational shaft of the motor are directly detected, the mechanical phase angle adjustment required for the conventional resolver is not required.