Solitary plasmacytoma of the lung are extremely rare, and are sorts of plasma cell dyscrasia which are characterized by the elaboration of excessive amount of immunoglobulin or their constituent units. We experienced one case of plasmacytoma on the left lower lobe which was treated by left pneumonectomy. It was proven that the plasmacytoma produced immunoglobulin M and kappa chain by immunofluorescent technique. During the follow up period, 2 1/2 years after surgical removal of tumor mass, there were no local recurrence and dissemination.