To provide an aqueous eye drop which has both an excellent anti-viral medicinal effect and excellent safety.

This aqueous eye drop contains (-)-9-[1'S, 2'R-bis(hydroxymethyl)cyclopropan-1'-yl] methylguanine or its pharmaceutically acceptable salt as an active ingredient. The aqueous eye drop for ophthalmic treatments contains the active ingredient which has a higher medicinal effect and safety than those of acyclovir and ganciclovir and whose anti-viral medicinal effect can advantageously be used for a therapeutic effect, and is excellent for viral ophthalmic diseases.