An optical disk of a system wherein a recording layer is to be irradiated throughout a thin film cover layer with a laser beam, wherein a hard coat layer (W) is formed on the thin film cover layer, and the hard coat layer (W) is made of a cured product of coating composition (X) comprising a polyfunctional compound (A) having at least two active energy ray curable polymerizable functional groups, a water and oil repellency-imparting agent (B), an active energy ray polymerization initiator (C) and a colloidal silica (D) having an average particle size of from 1 to 200 nm, provided that the water and oil repellency-imparting agent (B) is a water and oil repellency-imparting agent (B-T) having, in one molecule, a moiety (b-1) excellent in compatibility with the polyfunctional compound (A) and an active energy ray curable functional group (b-3). In the optical disk of the present invention, the hard coat layer formed of the surface of the thin film cover layer is excellent is abrasion resistance, transparency and long-term sebum stain proofness, particularly removability of fingerprints attached to its surface.