The cationically photopolymerizable composition according to the present disclosure includes: (A) a polyfunctional epoxy compound having two or more epoxy groups per molecule; (B) a monofunctional epoxy compound having one epoxy group per molecule; (C) a photocation generator; and (D) an oxetane compound. At least one of the component (A) and the component (B) contains an epoxy compound ((A1) or (B1)) having a polyether backbone per molecule. A mass ratio of the component (A) to the component (B) falls within a range of 90:10 to 30:70.