A displacement sensor includes an emitting unit periodically emitting pulse signals; a receiving unit receiving reflection signals generated from the pulse signals and reflected by an object and outputs binary signals that indicate signal intensity of the received reflection signals; a waveform summation unit generating a summation waveform by accumulating temporal waveforms of the binary signals for the respective corresponding periods of time with reference to emission timings of the corresponding pulse signals; a distance calculation unit calculating a value that indicates a distance to the object on the basis of waveform features corresponding to waveform features of the pulse signals that appear in the summation waveform; and a reception signal amount calculation unit calculating a reception signal amount that is intensity of the reflection signals received by the receiving unit on the basis of feature amounts indicated by cumulative values that appear in the summation waveform.