A 74-year-old man was admitted to our hospital complaining of dyspnea. Parasternal transthoracic echocardiography showed a quadricuspid pulmonary valve above the aortic valve and a hypoplastic accessory cusp between the right and left cusps of the pulmonary valve. The pulmonary valve ring diameter was normal (26 mm) but the transvalvular peak velocity was 3.5 m/sec, suggesting a pressure gradient of 49 mmHg across the pulmonary valve. The pulmonary valve had thickening and decrease in mobility of the leaflets without complete closure during diastole, and severe pulmonary regurgitation was present. Heart failure was treated successfully with digitalis and diuretics. Quadricuspid pulmonary valve is difficult to identify using transthoracic echocardiography because of the anatomical features. In this case, the dilated main pulmonary artery caused the pulmonary valve orifice to shift anteriorly, allowing visualization of the short-axis view of the pulmonary valve.