Localized solitary plasmacytoma of the bone (SPB) is a rare disease and is characterized by only one or two isolated bone lesions with no evidence of disease dissemination. A previously healthy 44-year-old male was admitted for evaluation of an abnormal radiographic shadow in the left middle lung field with symptoms of left back pain. Radiological evaluation revealed a peripheral opacity in the left chest wall, which was highly suspected to be a chest wall tumor. CT-guided transcutaneous needle biopsy of the tumor was performed and the specimens showed a monomorphous population of mature plasma cells. The bone marrow biopsy findings revealed no evidence of myeloma and bone scanning revealed only abnormal accumulation in the left seventh rib. He had mild M-proteins in a urine sample and Bence-Jones protein was detected. Immunoelectrophoresis revealed mild biclonal gammopathy of Bence-Jones protein of both the kappa and lambda light-chain types. Under a diagnosis of solitary bone plasmacytoma, preoperative radiation therapy with doses of 40 Gy for the tumor was performed. He underwent complete en bloc resection of the chest wall, including one-third of the left sixth and seventh ribs, the intercostal muscle and the parietal pleura. The protein abnormalities in the urine sample disappeared following surgical resection. Adjuvant chemotherapy using melphalan and prednisolone was performed. He is doing well without evidence of tumor recurrence 2 years following his initial diagnosis.