A disc apparatus includes: a housing; a recording/reproducing unit provided in the housing for recording and/or reproducing information in and/or from a disc-shaped recording medium; an insertion/ejection port provided on the housing through which the disc-shaped recording medium is inserted and ejected, the insertion/ejection port having a width greater than the diameter of the disc-shaped recording medium; a disc transport mechanism provided in the housing to transport the disc-shaped recording medium between the insertion/ejection port and the recording/reproducing unit; and an identification mechanism to identify the disc-shaped recording medium as a first disc-shaped recording medium having a first diameter or a second disc-shaped recording medium having a diameter smaller than the first diameter The identification mechanism includes a pair of levers, a pair of gear members, urging means, a stopper, first detection means, and control means.