Supplementary motor aphasia results from impairment of the supplementary motor area in the left mesial frontal cortex. We report a rare case of subarachnoid hemorrhage presenting with supplementary motor aphasia as an initial symptom. A 52-year-old woman was brought to our hospital by ambulance due to sudden severe headache and supplementary motor aphasia. CT demonstrated subarachnoid hemorrhage that appeared to be particularly thick in the pericallosal cistern. She had undergone neck clipping of a left vertebral artery aneurysm for subarachnoid hemorrhage 14 years earlier. At that time, she underwent neck clipping of a de novo anterior communicating artery aneurysm. The postoperative course was uneventful and supplementary motor aphasia had disappeared in 4 weeks. To our knowledge, this is the first reported case of subarachnoid hemorrhage presenting with supplementary motor aphasia as an initial symptom. In this case, adhesion of the arachnoid membrane resulting from old subarachnoid hemorrhage might have prevented new subarachnoid hemorrhage from spreading diffusely. Hematomas spread mainly into the pericallosal cistern from ruptured aneurysm of the anterior communicating artery. Therefore, thick hematoma in this cistern might have compressed the supplementary motor area, resulting in supplementary motor aphasia. Aphasia disappeared as pressure from the hematoma dissipated. Neurosurgeons may be likely to encounter a patient showing a transient consciousness disturbance after the use of the anterior interhemispheric approach or within a period of vascular spasm. Supplementary motor aphasia might also be included in such consciousness disturbance. Supplementary motor aphasia might be a reversible symptom if there is no irreversible damage to the supplementary motor area by infarction or intraparenchymal hemorrhage.