This report presents the case of a 51-year-old female who was admitted to a local hospital because of a persistent headache. A diagnosis of multiple cerebral infarctions was thereafter made, but there was no evidence of either atherosclerosis or atrial fibrillation. The case was thought to be a cryptogenic stroke, however, Doppler ultrasonography of the lower extremities showed venous insufficiency. Transesophageal echocardiography revealed a secundum atrial septal defect (ASD) with a left to right shunt. Therefore, the final diagnosis was paradoxical brain emboli, and transcatheter ASD closure was successfully performed by cardiologists without any sequelae.