We present a case of a 63-year-old female who underwent an excision of a left atrial myxoma. Previously, she had been diagnosed with multiple myelomas and received radiation therapy and chemotherapy. A left atrial myxoma was found at an annual medical check-up. The myxoma was removed via a right minithoracotomy with peripheral cannulation to minimize bleeding complications and surgical site infection. She was transferred to the referring hospital on postoperative day 7 due to recurrence of multiple myelomas. She was doing well 14 months after the operation. Right minithoracotomy is a useful approach to minimizing the risks of bleeding and infection in patients with multiple myelomas.