The patient, a 69-year-old woman, had been diagnosed with a heart murmur. A chest X-ray at a local clinic had shown an abnormal shadow. Since CT revealed a 3-cm-diameter mass close to the pulmonary artery, we performed a coronary angiography and diagnosed her as having a coronary artery aneurysm associated with a coronary-pulmonary artery fistula. We incised the aneurysm under cardiac arrest, the wall of which had three openings that were suture closed from the inside and outside. The coronary-pulmonary artery fistula was suture closed. A postoperative angiography confirmed the disappearance of the coronary artery aneurysm and the abnormal blood vessels. The patient had an uneventful postoperative course and was discharged on postoperative day 15. We report a rare case of coronary-pulmonary artery fistula with a coronary artery aneurysm for which surgery was followed by an uneventful postoperative course.