A 78-year-old woman presented with leg edema and exertional dyspnea. Echocardiography revealed a smooth-surfaced mass adjacent to the left atrium in the pericardial cavity with a massive pericardial effusion. Pericardiocentesis resulted in the drainage of a bloody effusion. Magnetic resonance imaging documented a mass having isointensity on T1- and hyperintensity on T2-weighted images. In addition, the mass was evenly enhanced with gadolinium 10min after administration. By surgical resection, a 25×30mm in diameter tumor was excised together with a left atrial wall portion. The pathological examination made a final diagnosis as hemangioma. Based on these findings, we report the rare case of pericardial hemangioma with a bloody pericardial effusion, which presented with heart failure symptoms. Although bloody pericardial effusion is considered a supportive characteristic for malignant tumors, we could preoperatively make a precise diagnosis of benign hemangioma by means of several imaging modalities.