Primary extramedullary plasmacytoma is a rare plasma cell neoplasm. Extramedullary plasmacytomas are most commonly found in head and neck region, but it can occur at other sites occasionally. Involvement of ovary by this tumor is exceedingly rare. Here, we report a case of primary ovarian plasmacytoma in a 47-year-old woman. The patient presented with a lower abdominal pain and a left ovarian mass (12 cm × 10 cm) was detected during the ultrasonographic examination. The patient underwent hysterectomy with bilateral salpingo-oophorectomy. Subsequent histopathologic, immunohistochemistry, bone marrow examination, and other relevant examinations established the diagnosis of primary ovarian plasmacytoma. The patient did not receive the postoperative chemotherapy and 6 months follow-up was uneventful.