A holographic recording/reproducing apparatus includes a splitter unit for splitting a laser beam into a first laser beam for generating a signal beam and a second laser beam which serves as a reference beam, a spatial light modulator for spatially modulating the first laser beam in accordance with information to be recorded, the modulated first laser beam serving as the signal beam, and a first lens system for focusing the signal beam and the reference beam onto a holographic recording medium. In a recording process, the signal beam and the reference beam are guided through one and the other half-regions separated along the optical axis of the first lens system. In a reproduction process, only the reference beam is guided through one of the half-regions and a signal reproduction beam from the holographic recording medium is guided through a second lens system in the other half-region.