The incidence of primary malignant cardiac tumor, especially a primary cardiac sarcoma is extremely rare and seldom causes symptoms until late in its course. Early recognition of tumor is vital because it allows prompt and proper management. We report a rare case of cardiac sarcoma who presented as a hemopericardium after straining. Right atrial mass was diagnosed by transesophageal echocardiography (TEE) that was performed to investigate the cause of hemopericardium.