A photosensitive composition comprising: a sensitizing dye represented by the formula (I) defined herein, in which Z represents a substituted divalent linking group forming a 5-membered or 6-membered ring, provided that a total volume of substituents arranged on the 5-membered or 6-membered ring formed by Z is 200 .ANG..sup.3 or more; R.sub.1 represents a hydrogen atom or a monovalent non-metal atomic group; A represents a substituted or unsubstituted aromatic ring or hetero ring; and R.sub.1 and A may be taken together to form an aliphatic or aromatic ring; an activator compound being capable of causing a chemical change due to a mutual action with an electron excited state to be generated by light absorption of the sensitizing dye, thereby generating a radical or an acid; and a polymerizable compound being capable of reacting with at least one of a radical and an acid.