We report a case of minimally invasive cardiac surgery treated by small right intercostal thoracotomy for left atrial myxoma after substernal reconstruction of the esophagus using gastric interposition. This technique could not only alleviated risk at the second median sternotomy, but was also minimally invasive. A 63-year old man was admitted to our hospital for complaints of right upper limb asthenia and slight fever. Computed tomography showed cerebral infarction. Moreover, cardiac ultrasonography showed a giant myxoma in the left atrium. We thought that it was impossible to reperform median sternotomy, because there was high risk of injury to the reconstructed esophagus using a gastric duct behind the sternum. The patient underwent excision of the myxoma by the right intercostal thoracotomy approach, and did well. He was discharged from the hospital without any complications.