An apparatus for automatically exchanging a number of record medium cassettes includes a housing, a cassette storing device arranged within said housing for storing the cassettes, recording and reproducing devices arranged within said housing for recording and reproducing information on and from the record medium cassettes, a cassette transporting device arranged within said housing for transporting a plurality of cassette hand over units, a mail box having a cassette supply room and a cassette receipt room, a transport unit for transporting the cassettes between the cassette hand over units and the mail box. By using a plurality of cassette hand over units, the cassettes can be transported efficiently. By using the mail box, a new cassette can be automatically supplied into the housing and an unnecessary cassette can be automatically removed from the housing.