A disk apparatus is provided that includes an apparatus body including a driving section for rotating a disk, an information reading/writing section, and a control section for controlling the driving section and the information reading/writing section. The disk apparatus also includes a housing accommodating the apparatus body and including a housing body having an accommodating recess formed at a position thereof corresponding to the driving section and the information reading/writing section for accommodating the disk therein, and a lid member supported for pivotal motion on the apparatus body for closing up the accommodating recess. The accommodating recess has a convex portion formed in a projecting manner on a bottom face thereof such that the convex portion surrounds the disk mounted around a rotary shaft of the driving section A space which is formed by the convex portion surrounds the disk having a circular shape and a polygonal shape combined.