Primary cardiac lymphoma (PCL) is defined as lymphoma involving only the heart and/or pericardium, or with an intrapericardial location of the main tumor mass. It is an extremely rare type of lymphoma and has a poor prognosis because of diagnostic delay and the disease site. PCL is histologically characterized by a mostly diffuse large B-cell lymphoma. The median survival time has been reported to be 7 months. We present the case of a 55-year-old woman who presented with chest oppression and dyspnea on effort. Following a close examination, PCL with a high International Prognostic Index was diagnosed. She received 6 courses of R-CHOP therapy (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone) and achieved complete remission. The patient then underwent a consolidation therapy consisting of high-dose chemotherapy including rituximab, followed by autologous peripheral blood stem cell transplantation. There were no complications, such as pulmonary embolism, fatal arrhythmia, or acute heart failure, throughout chemotherapy. Our experience indicates that this therapy is safe and effective and can improve the outcome of high-risk PCL.