With branched epoxy(meth)acrylate which comprises a phenyl skeleton serving as a stiff molecular skeleton, and which comprises in the molecular skeleton a number of branched structures capable of forming a coating structure at a high crosslinking density after ultraviolet curing, it becomes possible to design the coating hardness to be high even if the content of an acryloyl group is designed to be low to effect less crosslinking reaction induced by ultraviolet curing, and it becomes possible to relax distortions inside a cured film due to cure shrinkage which occurs at the time of ultraviolet curing. As a result, there can be realized an ultraviolet-curable composition for an optical disk which has a high elastic modulus and is less tilted at the time of curing even if the coating hardness is designed to be high.