A 34-year-old woman was diagnosed as primary mediastinal diffuse large B-cell lymphoma, treated by cyclophosphamide, doxorubicin, vincrisitne, prednisolone (CHOP) chemotherapy and radiation therapy, and received high-dose ranimustine, cytarabine, etoposide, cyclophosphamide (MCVAC) chemotherapy with autologous peripheral blood stem cell transplantation. Seven years after complete remission was achieved, she recognized dyspnea and was diagnosed secondary interstitial pneumonitis caused by chemotherapy and/or radiotherapy. Because her symptoms and pulmonary function got worsen gradually, she underwent lung transplantation from a brain death donor when she was 47-year-old. She has successfully rehabilitated and returned to her life without oxygen inhalation therapy.