PURPOSE:To highly precisely position a reticule and a wafer through a projecting optical system in a positioning device used in various exposing devices by correcting the convergence error in an alignment wavelength different from an exposing wavelength, and imaging a positioning mark image on the reticule onto the wafer through a correcting optical system and a lens. CONSTITUTION:A first positioning mark 5 provided on a first object 1 situated on the object surface of a projecting optical system, a second positioning mark 6 provided on a second object 2 situated on the image surface of the projecting optical system, and a light source 4 emitting a coherent alignment light of two frequencies having a wavelength different from an exposing wavelength are provided. A correcting optical system 7 for correcting the convergence error of the projecting optical system so as to perform a precise imaging onto the second object surface in conformation to a specified area where an interference fringe is formed on the first object, a spatial filtering optical system 13 for removing a speckle pattern from the light returned from the second positioning mark 6, and a light detecting means 15 for detecting a light beat signal from the light transmitted through the space filtering optical system are provided.