A composition exhibiting significantly increased luminance as compared with that of a known luminescent composition is provided. The composition constitutes a system in which chemiluminescence is effected by mixing two types of compositions and includes a composition A in which an oxalic ester is present in a solid state in a solution containing the oxalic ester and a luminescent substance both dissolved therein and a composition B in which aqueous hydrogen peroxide and a catalyst is dissolved in a solution.