To provide a confocal displacement sensor capable of easily and accurately measuring displacement of a measurement object. Light having a chromatic aberration is converged by a lens unit 220 and irradiated on a measurement object S from a measurement head 200. Light having a wavelength reflected while focusing on the surface of the measurement object S passes through the optical fiber 314 in the measurement head 200. The light passed through the optical fiber 314 is guided to a spectral section 130 in a processing device 100 and spectrally dispersed. In the processing device 100, the light spectrally dispersed by the spectral section 130 is received by a light receiving section 140. A light reception signal output from the light receiving section 140 is acquired by a control section 152. The control section 152 measures displacement on the basis of the acquired light reception signal and gives the light reception signal to a PC 600 on the outside. A CPU 601 of the PC 600 causes a display section 700 to display, as change information, a change from a light reception signal acquired at a point in time before a present point in time to a light reception signal acquired at the present point in time.