The incidence of blindness after aneurysm surgery is very rare. We experienced a case of unilateral blindness after internal carotid artery[ICA] aneurysm wrapping. A 43-year-old male immediately developed ipsilateral ocular pain and visual loss in his left eye after the treatment of a lateral ICA aneurysm by wrapping with muscle pieces. He had also multiple aneurysms, which were multilobulated anterior communicating artery [A-com], middle cerebral artery[MCA] and posterior communicating artery [P-com] aneurysms. Coilings were done for a part of A-com artery aneurysm and P-com artery aneurysm on admission. The remaining A-com artery aneurysm was clipped and ICA aneurysm was wrapped with temporal muscle piece. A retrobulbar optic neuropathy might have resulted from either direct injury or damage to small dural vessels of the posterior optic nerve. Actually, the optico-carotid space was tight and the optic nerve was compressed by swollen muscle piece. Despite releasing of compression of the optic nerve on second day, his visual loss was irreversible.