A 35-year-old man was followed up for systemic lupus erythematous with antiphospholipid antibody-positive. He underwent an echocardiogram for a closer examination of his heart murmur. Transthoracic echocardiography revealed a calcified mass of 30 mm in diameter in the right ventricular outflow tract. Surgery was performed through an upper hemi-sternotomy. After establishment of beating-heart cardiopulmonary bypass, the pulmonary trunk was opened with a longitudinal incision. The highly calcified mass was located immediately below the pulmonary valve. We exfoliated the mass from the right ventricle, and resected it en bloc during short-term cardiac arrest. The postoperative pathological diagnosis was a calcified amorphous tumor. The patient was discharged from our hospital on postoperative day 12．No tumor recurrence was observed 9 months after the surgery.