An object of the present invention is to provide a cationic curable composition which has low viscosity, can be rapidly photo-cured even in the air, has good adhesion to a substrate such as glass or resin, and is excellent in glass cleaner resistance and water resistance; an ink jet ink, a gravure ink and a hard coating material which comprise the composition; and cured products thereof. A cationic curable composition comprising: (A) 1 to 100 parts by weight of a phenol derivative having 3 or more aromatic rings per molecule, wherein the aromatic ring has a structure in which some or all of hydrogen atoms of phenolic hydroxyl groups of the aromatic ring are substituted by polymerizable functional groups; (B) 1 to 500 parts by weight of a cationic polymerizable compound; and (C) 0.05 to 20 parts by weight of a photo- and/or thermo-cationic initiator is provided.