To provide a rotational position sensor, a combined rotational position sensor, and an electric power steering apparatus allowing to detect the rotational position of a rotation detecting shaft represented by a steering shaft.

The compound rotational position sensor 34 determines how many revolutions the steering shaft 32 has made on the basis of a reference position by the rotational position sensor 52 and determines a rotational angle in one revolution of the steering shaft 32 by an encoder 51. On the basis of the two pieces of rotational position information, the rotational angle of the present steering shaft 32 can be determined as an absolute rotational angle on the basis of the reference position. The steering shaft 32 and a base part 50 form a closed magnetic circuit, thereby increasing the efficiency of electromagnetic induction to reduce power consumption.

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