A 66-year-old male with hypertension was referred for evaluation of abnormal find chest X-ray. A computed tomography (CT) scan revealed a solitary pericardial mass with a diameter of 5 cm, located in the left atrioventricular groove. It showed solid but unevenly enhanced contents suggesting a well vascularized tumor originating in either a part of the left heart or the pericardium. As magnetic resonance imaging showed a clear boundary between the tumor and the pericardium, cardiac origin was suspected. Surgical removal of the tumor was performed via median sternotomy. The tumor originated from the lateral aspect of the left atrial appendage, having a base of 10 mm in diameter. The tumor was fully excised with an associated left atrial cuff under cardiopulmonary bypass. The postoperative course was uneventful. The tumor was histopathologically diagnosed as cavernous hemangioma originating in the left atrial wall. There has been no sign of recurrence for four years following surgery.