We report our experience with a case in which primary signet-ring cell carcinoma of the uterine cervix was successfully treated with CPT-11 plus S-1 therapy. The patient was a 45-year-old woman with stage IIIB primary signet-ring cell carcinoma of the uterine cervix. The uterine cervix had enlarged to 8 cm; the right ovarian tumor was 15 cm in size; and there was an 8-cm cystic mass in the left ovary. After five cycles of CPT-11 plus S-1 therapy, the tumor shrinkage rate was 52.2% and the tumor response was partial response. To improve symptoms, left adnexectomy was performed, and CPT-11 plus S-1 therapy was continued. To date, 11 cycles have been performed without dose reduction or delay of therapy. No adverse event of grade 3 or higher has been observed. CPT-11 plus S-1 therapy was effectively and safely performed to treat signet-ring cell carcinoma of the uterine cervix that is difficult to treat. This is the first case in which primary signet-ring cell carcinoma of the uterus responded well to CPT-11 plus S-1 therapy.