Plasma cell granuloma (PCG) is an uncommon benign tumor of unknown etiology, primarily located in the lungs. We report a case of PCG on the gingiva mimicking benign and malignant tumors in a 56-year-old woman. Histopathological examination revealed a relatively sharp circumscribed inflammatory cell infiltration under the mucosa-containing plasma cells, predominantly those including Russell bodies. Plasma cells are stained by CD138 immunohistochemistry. Polyclonal status of the lesion was confirmed by kappa and lambda light chaining. The typical histopathological and immunohistochemical findings in combination with the clinical features were consistent with PCG, about which the literature reports very few cases.