A disc device includes: a casing including: a casing body that has a housing section of a disc 4 and houses a device body including a drive unit for rotating the disc 4; and a cover section rotatably supported on the casing body for closing the housing section. The casing includes: a rotation stop mechanism 5 for stopping rotation of the disc 4 when the cover section is opened. The rotation stop mechanism 5 includes a lever 6 rotatably supported on the casing body and having a contact section 631 contacting with the disc 4 when the cover section is opened; a biasing unit 7 provided on the lever 6 for biasing the contact section 631 toward an edge face of the disc 4; and a first releasing unit 13B provided in a protruding state on the cover section, the releasing unit 13B contacting with the lever 6 to rotate the lever 6 for releasing contact between the contact section 631 and the disc 4 when the cover section is closed. The contact section 631 has a contact face 632 inclined against the rotational tangent direction of the disc 4.