Clear cell carcinoma (CCC) of the uterine cervix without prenatal diethylstilbestrol exposure is rare, and its etiology is unclear. We present a case of cervical CCC presenting as a submucosal tumor, which strongly suggests an association between cervical endometriosis and cervical CCC. A 56-year-old postmenopausal Japanese woman visited a gynecologic clinic with a complaint of watery vaginal discharge. A few atypical cells suggesting adenocarcinoma were detected in a cervical cytologic specimen. Magnetic resonance imaging revealed a cystic lesion with a solid component at the uterine cervix. Under a tentative diagnosis of cervical cancer, surgery was performed. Although a freshly resected specimen initially showed no tumorous lesion in the cervical mucosa, cutting of the mucosa revealed a solid tumor with a final diagnosis of CCC. The findings of aggregation of hemosiderin-laden macrophages and ectopic endometrium adjacent to the tumor strongly suggest that this tumor arose from cervical endometriosis.