To provide a cationically photocurable composition that has an excellent contact with substrates such as glass and resins, and gives a cured product excellent in transparency, a coating material, and an ink for inkjet printers composed of the composition, and cured products thereof.

The composition includes an epoxy group-containing silane coupling agent having both cationic photocurability and silane coupling ability and a cationic photopolymerization initiator.