A position sensor is provided with a displacement signal output circuit 1 that amplifies an electromagnetically induced and detected current signal from a slider and converts the result to a rectangular wave signal; a phase difference detection circuit that compares the output signal from the displacement signal output circuit with a clock signal employed for producing the alternating current component from the scaler and detects the phase difference; and an interpolation pulse counter that determines digital displacement data from the phase difference detected at phase difference detection circuit using interpolation pulses. Further, an averaging circuit is provided at the output stage of this interpolation pulse counter which calculates and outputs an average value of a plurality of instances of digital displacement data successively calculated by the interpolation pulse counter.