A height-measuring device characterized by comprising an illumination optical system for illuminating the surface of a sample; a pair of imaging optical systems having a pair of optical axes symmetrically arranged on both sides of the optical axis of the whole optical flux reflected by the sample and converging part of the optical flux along the optical axes; a pair of light-detecting optical systems for detecting a light spot of which the position changes depending upon the height of the sample; and a height processing means for detecting a spot position signal based upon a light intensity signal from the pair of light-detecting optical systems and determining the height of the surface of the sample from the spot position signal.
