A disc-shaped recording medium and a recording/reproducing apparatus employing the disc-shaped recording medium as a recording medium, are disclosed. The recording medium has a diameter of not more than 80 mm, and a recording track is formed on the recording medium with a track pitch of approximately 1.6 µm. Information in excess of 130 Mbytes is recorded in a data compressed state on the recording track and the recording medium is rotationally driven at a constant linear velocity for recording and optically reproducing the information. The recording/reproducing apparatus employing the disc-shaped recording medium as a recording medium includes a buffer memory between a data compressing circuit for compressing input digital data and a recording encoding circuit for processing the compressed data by modulation suitable for recording, as long as a recording system of the apparatus is concerned, and a buffer memory between a playback decoding circuit for processing the compressed data by error correction decoding and demodulation complementary to the modulation and a data expansion circuit for expanding the compressed data to the original state. By suitably selecting the capacity of the buffer memories, recording and reproduction may continue satisfactorily even if the scanning position of the recording head and the optical head undergoes track jump during recording or reproduction.