PURPOSE: To obtain an optical type displacement meter which can execute correction so that a reflected light from a surface to be measured may pass on the optical axis of an optical system correctly when the surface has a tilt, and thus can execute highly-precise measurement.

CONSTITUTION: A light beam deflector 3 disposed in the optical path of a light from an objective lens 2 and a detecting device 5 of a focal position and a position in the laterteral direction which detects the focal position of the light from the light beam deflector 3 and the position in the lateral direction thereof, are provided. A light emitted by a laser diode 12 is made to enter a first polarization beam splitter 4 through a collimator lens 11, and the light reflected thereon passes through a 1/4 wave plate 8 and falls on a mirror 6. It is reflected by the mirror 6, passes through the objective lens 2 and illuminates a surface 14 to be measured. From the light reflected on the surface 14 to be measured, the focal position of a light flux and the position in the lateral direction of the light flux are detected. The focal position of the light flux shows the displacement of the surface 14 in the direction of the optical axis, while the position in the lateral direction of the light flux corresponds to a tilt of the surface 14.