PURPOSE: To detect distance information in a single action by providing a light source which emits beltlike, parallel light and a CC sensor which detects a belt image of light formed on the surface of an object by the emitted light from the light source as a two-dimensional beam of light.

CONSTITUTION: The emitted light beam 2 from the parallel light source 6 impinges on the surface of the object 3 of measurement and forms the belt image 9 of light on the surface of the object 3 of measurement. This belt image 9 of light is formed on the CCD sensor 8 by a reflected light beam 7 and detected as a belt 10 of light. Then, the image formed on the CCD sensor 8 consists of distance information in a direction Y and position information in a direction X. Then, the object of measurement is in a convex shape 3a, the belt image 10a formed on the CCD sensor 8 can be detected from the Y- directional position data when the distance is short at the center position and long at both end parts. Namely, the distance from the parallel light source to the object of measurement on a line irradiate with the emitted light from the parallel light beam is measured at a time.