The present invention provides a resin container in which an aqueous liquid preparation containing a prostaglandin F2α derivative having at least a fluorine atom in its molecule can be stored stably for a long period of time. By storing the aqueous liquid preparation containing the prostaglandin F2α derivative having at least a fluorine atom in its molecule in the resin container made of a propylene/ ethylene copolymer in which the ratio of a propylene component to an ethylene component is in the range of from 94.0/6.0 to 99.5/0.5 (propylene component/ethylene component), a decrease in the content of the prostaglandin F2α derivative in the aqueous liquid preparation is inhibited.
