We describe a case of ruptured sinus of Valsalva aneurysm (RSVA) with moderate aortic regurgitation (AR), which developed on the second day after admission. The AR was caused by a hemodynamic effect solely, in which the shunt blood flow through ruptured site pulled the right aortic cusp away from closure. The pathological mechanism of the AR was clearly visualized by intraoperative transesophageal echocardiography (TEE) and the AR was successfully resolved after simple closure of the RSVA without any additional procedure to the aortic valve.