An optical information recording and reproducing apparatus for recording information on a recording medium by forming interference fringes generated by interference between an information beam and a reference beam on the recording medium, and reproducing the information by irradiating the recording medium with the reference beam, in which the interference fringes are formed. The apparatus includes a spatial light modulator for spatially modulating at least a portion of the light beam emitted from a light source into the information beam, a light sensing device that reads the information beam extracted from the recording medium by the reference beam irradiated on the recording medium, a shift amount detector that detects a shift of an irradiating position of the light beam entering the spatial light modulator, and a device that corrects a positional shift between a position of an area for modulating the information beam and a position of the light beam in the spatial light modulator, based on a positional shift amount detected by the shift amount detector.