A photosensitive composition comprising: a sensitizing dye represented by the following formula (1): ##STR00001## in which A represents an optionally substituted aromatic ring or an optionally substituted hetero ring; X represents an oxygen atoms a sulfur atom, or --N(R.sub.6)--; and R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, and R.sub.6 each independently represents a hydrogen atom or a monovalent non-metal atomic group; an activator compound being capable of causing a chemical change due to a mutual action with light absorption of the sensitizing dye represented by the formula (1) so as to generate at least one of a radical, an acid and a base; and a compound being capable of reacting with at least one of a radical and an acid so that physical or chemical characteristics thereof change irreversibly.