Descemet's membrane detachment is an important reason for corneal endothelial decompensation after intraocular surgery. During cataract surgery, it is an unusual complication. We report a case of Descemet's membrane detachment in which approximately 60% of Descemet's membrane (DM) involving approximately the upper two-thirds of the cornea was torn out during a routine phacoemulsification. It caused diffuse corneal edema and blurred vision in the 2 months following the surgery. Topical prednisolone acetate (1%) and sodium chloride (5%) had been used for treatment, with slow improvement in the patient's symptoms and vision. Interestingly, the cornea regained clarity 2 months after surgery without further surgical treatment.