the present invention proposes a double disc insertion preventing apparatus for a disc player with a simple construction while improving thinning . with a double disc insertion preventing apparatus for a disc player of the present invention , a roller supporter having a rotation axis is provided at a position in the vicinity of a disc insertion port of the supporter , a roller is supported with the ability to rotate freely at the rotating end located further back than the rotation axis of the supporter , the disc insert detection switch is attached on the circuit substrate placed furthermore back than the roller , an actuator is rotated by interlocking with the rotating operation of the roller supporter when the roller allows disc insertion causing a double disc insertion preventing signal to be sent by controlling the switch by the actuator , and wherein the rotation axis of the actuator conforms to the rotation axis of the roller supporter , and the actuator controls the switch at a position furthermore back over the roller .