A 24-year-old woman, under the treatment for atypical depression, visited our emergency room on foot with a chief complaint that she stabbed herself in the chest with a sewing needle. Chest X-ray and plain CT showed the needle penetrating the chest into the heart. There was no sign of pneumothorax or cardiac tamponade. She was hemodynamically stable. Echocardiography revealed atrial septal defect (ASD) by chance. We performed urgent surgery for needle removal and ASD closure through median sternotomy. The needle was easily recognized near the right ventricle apex. The right atrium was opened, but the needle was not seen through the tricuspid valve because of trabecular formation. After the needle was removed, ASD was closed using the direct suture method. The needle was 35 mm long. She was transferred to the psychiatry department on postoperative day 4 and had a good postoperative course.