To improve the photostability of a composition containing ketotifens and an imidazoline derivative.

The photostability of the composition containing the ketotifen or its salt and an imidazoline compound expressed by formula (1) [wherein, Z is a hydrocarbon ring or a heterocyclic ring; R1 is a divalent group; R2 is a substituent; (m) is 0 or 1; and (n) is an integer of 0 to 6] is improved by blending an amino acid expressed by the following formula (2). H2N-(CH2)t-COOH (2) [wherein, (t) is an integer of 1 to 5].