Abstract: It is an object of the present invention to effectively prevent a bezel and a lid from deviating or coming off from each other. In a slot-in type disk apparatus, a base body 10 and a lid 20 constitute a chassis sheath, a front surface of the chassis sheath is provided with a bezel 30, the bezel 30 is formed with a disk-insertion opening 31, and a disk is inserted directly from the disk-insertion opening 31. The bezel 30 includes lid pawls 33A, 33B, 33C and 33D projecting toward the lid 20 from one of the bezel 30 which is in parallel to the disk-insertion opening 31. The bezel 30 also includes steps 32 formed on both sides of the lid pawls 33A, 33B, 33C and 33D. The lid 20 includes lid-side holes 27A, 27B, 27C and 27D which are engaged with the lid pawls 33A, 33B, 33C and 33D, respectively, and includes lid-side projections 28A and 28B formed on both sides of the lid-side holes 27A, 27B, 27C and 27D.

Abstract: An adapter A1 made of a synthetic resin includes an annular frame 1 having an outside diameter of 12 cm, a disk receiving section 2 provided continuously on a lower portion of an inner edge of the frame 1, and a pair of disk pressing sections 3 and 3 provided continuously on an upper portion of the inner edge of the frame 1. The disk receiving section 2 is provided with a circular opening 4 for causing an information recording area of a disk to face an optical reader of a disk player. A disk press-contact projection 7 formed so that a projection height is gradually increased in a disk rotation direction Y is provided on a lower surface of each disk pressing section 3. This adapter A1 can securely install a non-circular optical disk even if the optical disk has a slightly different size, and an installation operation of the non-circular optical disk can be easily performed.