We report a case of minimally invasive surgery (MICS) for left ventricular aneurysm with a large mobile thrombus, which appeared after chemotherapy for malignant lymphoma. A 42-year-old man with a postinfarction left ventricular aneurysm was admitted to our hospital to receive chemotherapy for malignant lymphoma. Eight days after the first administration of anticancer drugs, echocardiography revealed a large mobile thrombus in the left ventricular aneurysm that was absent on admission. The patient was referred to our department, and left ventricular endoplasty was performed through a small left thoracotomy. He recovered rapidly, and chemotherapy was resumed a month after surgery. This suggests MICS to be a valuable option for left ventricular aneurysm repair.