PURPOSE: To provide the titled composition capable of keeping the original fluorescence even after the outdoor use for a long period, having improved durability, and suitable especially as a film or sheet, by compounding a synthetic resin with at least two kinds of fluorescent agents wherein the difference between the wavelengths corresponding to the excitation peaks of the agents is larger than a specific value.

CONSTITUTION: Two or more kinds of fluorescent agents are added to a base synthetic resin in an amount of 0.1W1wt%. The fluorescent agent is, e.g. an organic fluorescent agent such as diaminostilbenedisulfonic acid derivative, etc., and an inorganic fluorescent agent such as Eu-doped yttrium vanadate, etc. The combination of the agents is arbitrary, i.e. organic-organic, inorganic-inorganic, or organic-inorganic; however, it is necessary that the wavelengths corresponding to the excitation peaks of two kinds of the fluorescent agents in the combination is separated from each other by at least 10mμ.