PURPOSE: To obtain the optical information recording/reproducing device provided with an optical pickup of a waveguide type for reducing a shift of a condensing point caused by a fluctuation of light source wavelength, and the influence exerted on a focus error signal by placing in parallel two pairs of waveguide mirrors of the same type.

CONSTITUTION: An emitted light from a light source is condensed to an optical information recording medium through an optical system, and a reflected return light from the optical information recording medium is coupled to an optical waveguide layer 8 by a coupler 3. The coupled luminous flux is propagated into the optical waveguide layer 8, made incident on two waveguide concave mirrors 13a, 13b of the same type placed in parallel and divided into two. Subsequently, two luminous fluxes reflected and focused by the concave mirrors 13a, 13b are made incident on waveguide convex mirrors 14a, 14b and reflected, and photodetected by photodetectors 11a, 11b and 11c, 11d provided in a substrate 10. Accordingly, a shift of a condensing point caused by a fluctuation of light source wavelength and the influence exerted on a focus error signal are reduced.