Recently, a case of cervical cancer on the mucosal surface of a pedunculated cervical leiomyoma had been reported. We experienced a similar but distinct case of microinvasive squamous cell carcinoma on the mucosal surface of a pedunculated submucous leiomyoma. A 45-year-old Korean woman underwent type I hysterectomy for heavy bleeding from pedunculated submucous leiomyoma. Histopathological examination revealed that the leiomyoma of which mucosa was covered focally by microinvasive squamous cell carcinoma. During the management of pedunculated leiomyoma protruding through cervix, caution must be taken because of, although rare instance, a possible coexisting malignancy.