To provide an apparatus and a method for recording/reproducing optical information for managing the wavelength of a light source in recording/reproduction of information by using holography and for limiting the in-medium wavelength of a fringe pattern in a medium, and an optical information recording medium.

In a step of recording/reproducing information in/from the optical information recording medium 1 by a pickup 11, a reference wavelength recorded in a storage area 1a of the optical information recording medium 1 is detected by a wavelength detection circuit 90, and based on the detected reference wavelength, the wavelength of the light source 301 for the pickup 11 is adjusted to an optimum wavelength by a controller 89. Then, when a temperature detected by a temperature sensor 91 indicates a prescribed change, the wavelength of the light source 301 for the pickup 11 is readjusted to the optimum wavelength.