There is provided a data processing device able to surely eject a recording medium out of a main body of the device even when the recording medium is received in a case while a locking member having adherence and elasticity of the case is locked with a center hole of the recording medium.A CD player includes: a main body of the device 3; a carrying unit 5 for ejecting and retracting a CD 2 from the main body of the device 3; a clamping and reading out unit 6 for reading out data recorded on the CD 2; and a microcomputer 4. The carrying unit 5 includes: a disc guide 17; and a roller arm 18 having a carrying roller 20. The microcomputer 4 makes the turntable 26 of the clamping and reading out unit 6 rotate while the CD 2 is held between the disc guide 17 and the carrying roller 20 when the carrying unit 5 fails to eject the CD 2 out of the main body of the device 3.