To obtain an ultraviolet-curable composition having high adhesive strength to many surfaces of polycarbonate, aluminum, silver alloy, gold, silicon, etc., and slight reduction in adhesive strength before and after being allowed to stand in a high-temperature and high-humidity environment for many hours and is useful for an optical disk having excellent durability.

The active energy ray-curable composition for an optical disk comprises a radically polymerizable compound and a polymerization initiator. The radically polymerizable compound contains a compound represented by formula (1) (R1 is a 2-16C alkylene group which may contain a branched chain; R2 is a hydrogen atom or a methyl group; X is a 2-40C organic group which may contain an oxygen atom, a sulfur atom or an aromatic ring; n is an integer of 1-10).