The purpose of the present invention is to identify a combination of drugs for the prevention or treatment of glaucoma or ocular hypertension, said combination being useful as a prophylactic or therapeutic agent for glaucoma or ocular hypertension. Combining sepetaprost and an Rho-kinase inhibitor enhances the intraocular pressurelowering effect in comparison to when either drug is used alone. The drugs may be administered concurrently or as a combination drug.