A 64-year-old man who had aortic valve regurgitation underwent aortic valve replacement. There had been no history of angina pectoris or taking of calcium channel blockers. When the operation was nearly completed, unexpected hemodynamic collapse happened without ST-segment changes on the ECG monitoring. Resuscitation was successful by cardiac massage, pacing and administration of catecholamine. Thereafter the same episodes occurred several times. At the 6th attack on postoperative day 7, we confirmed the ST-segment elevation using 12-lead-ECG, thus coronary artery spasm was diagnosed. Thereafter calcium channel blocker and coronary vasodilator were administered continuously. There has been no attack since postoperative day 13. Though postoperative coronary arteriography showed no anatomical changes compared with preoperative study, direct injection of ergonovine made the right coronary artery spastic, but not the left. We emphasized that perioperative coronary artery spasm may happen not only in the coronary artery surgery but in any other cardiac operations.