A 53-year-old man came to our hospital complaining of painful induration in the left scrotum. It was difficult to determine by manual palpation whether the induration was derived from the testis or paratesticular tissues including epididymis. Computerized tomographic scanning and ultrasonography revealed a left paratesticular mass, 3 cm in diameter, with unclear margin of the atrophic testis, which was suspected as originating from the epididymis. Although tumor extirpation was intended, he underwent inguinal orchiectomy due to strong adhesion of the mass to the ipsilateral atrophic testis. The tumor was opalescent, gum elastic, and solid, measuring 5 x 3 x 2 cm in size. Histopathological examination revealed a primary leiomyoma of the epididymis. The details of this rare case of primary epididymal leiomyoma that originated from the epididymal tail are reported herein.