Provided is an agent for treating or preventing a corneal endothelial disorder wherein cell proliferation is required. More specifically, provided is an agent for treating or preventing a corneal endothelial disorder, wherein cell proliferation is required, said agent comprising a p38MAP kinase inhibitor. In a preferred embodiment, the corneal endothelial disorder is a wound. In a preferred embodiment, the p38MAP kinase inhibitor is soluble in water. The p38MAP kinase inhibitor may comprise 4-[4-(4-fluorophenyl)-2-(4-methylsulfinylphenyl)-1H-imidazole-5-yl]pyridine (SB203580) or a salt thereof.
