To surely operate a cover opening-and-closing mechanism of a recording-and-reproducing device for a disk-shaped recording medium with a simple structure.

A rotation shaft 55, which erects, a slide member 48 having a stopper pawl of a cover opening-and-closing mechanism provided on a recording-and-reproducing device main body side, the stopper nail engaging with a lock pawl provided on a disk cover, and a rotation lever 49 which restricts the sliding position of the slide member 48 to a prescribed position on a base plate 51, comprises two components, that is, a caulking shaft 55a and an intermediate shaft 55b to form a prescribe gap both with the flange part 55-1 of the caulking shaft 55a and with the flange part 55-4 of the intermediate shaft 55b. Accordingly, when the shaft part 55-5 of the calking shaft 55a is calked to fix it to the base plate 51, the deformation of the member due to the calking force does not interfere the rotational operation of the rotation lever 49.