A case of plasmacytoma in the left maxillary alveolar process with buccal lymph node involvement is reported. The patient was a 74-year-old man who had swelling of the left side of the maxillary gingiva. An incisional biopsy was performed, resulting in a diagnosis of plasmacytoma. There were no abnormal findings in serum protein, urinary protein, or bone at other regions. The patient underwent partial maxillectomy with subsequent radiotherapy. The present case was diagnosed to be IgA-λ type plasmacytoma by means of immunohisto-chemical study. There has been no evidence of local recurrence, lymph node metastasis, or transition to multiple myeloma as of 1 year 10 months after surgery. However, long-term follow up is required.