The present invention relates to a recording/reproducing device that records data on a double-sided recordable optical disk for storage and management purposes. The device includes a unit which stores a plurality of optical disks, a unit which records data onto and reproduces data from an upper side of an optical disk, a unit which records data onto and reproduces data from a lower side of an optical disk, a unit which conveys an optical disk between the disk storage unit and each recording/reproducing unit. When a request for reading data recorded on the lower side of the disk is received while the upper side is being written onto, a control unit interrupts a data recording process on the upper side, reproduces data recorded on the lower side, and after completion of reproducing the recorded data, resumes the interrupted data recording process.