In an information recording medium from which information recorded on each pit is reproduced by an optical detection system that obtains a reproduced signal corresponding to each pit by scanning the information recording medium along pit rows by a light beam, data of high recording density can be accurately reproduced by a simple arrangement by shifting in a step-wise fashion edge positions of an information pit from a predetermined reference position in response to digital information to be recorded within a range corresponding to a predetermined shift period smaller than a transition period of a reproduced signal determined in response to a transfer characteristic of the optical detection system. Therefore, a nonlinear intersymbol interference can be reduced without emphasizing a noise component.