Leiomyoma is a benign tumor of smooth muscle and is rarely seen in ovary. A 46-year-old woman was performed on total abdominal hysterectomy and bilateral salpingo-oophorectomy because of the ovarian mass. Macroscopically, a tumor mass which is 3.5x2x2 cm in size was recognized in the ovary. In the microscopic examination, the tumor consisted of packets or bundles of smooth muscle fibers without significant cellular pleomorphism, necrosis and mitotic activity. The tumor was stained yellow colour with van Gieson stain. Immunohistochemically, smooth muscle actin (SMA) and desmin was positive but S-100 protein was negative in tumor cells. This case was evaluated as leiomyoma with these findings. There was not uterine leiomyoma. In this report, the diagnosis and differential diagnosis of ovarian leiomyoma was discussed in view of the literature.