A 43-year-old woman was diagnosed with an intravenous leiomyomatosis at a previous hospital and transferred to our hospital to undergo surgical treatment. Emergency one-stage operation for coincidental removal of intra-abdominal, right atrial, and intravenous masses were planned. Upon arriving at the operating room, she suffered a sudden onset of severe dyspnea and showed hemodynamic instability. Intraoperative TEE showed pulmonary embolization of a right atrial mass. Removal of the pulmonary artery mass and the intra-abdominal mass, and the cardiopulmonary bypass were performed without any complications.