A 43-year-old woman was admitted with heart murmur. Transthoracic echocardiography (TTE) and aortgraphy revealed severe aortic regurgitation and also transesophageal echocardiography (TEE) and multi-row detector computed tomography (MDCT) demonstrated quadricuspid aortic valve. Combined cardiac surgery such as aortic valve replacement and replacement of the ascending aorta was successfully performed. Quadricuspid aortic valve is a rare anomaly. MDCT is a useful device for the morphological and functional evaluation of the aortic valve disease non-invasively.