A curable composition of the present invention includes a cationic polymerizable compound; a thermal polymerization initiator; and a storage stabilizer, in which the cationic polymerizable compound includes at least two selected from the group consisting of a glycidyl ether compound, an alicyclic epoxy compound, and an oxetane compound, a content of the thermal polymerization initiator is from 0.3 to 3 parts by mass with respect to 100 parts by mass of the cationic polymerizable compound, and chain curing is enabled by thermal energy generated by a polymerization reaction of the cationic polymerizable compound.