This study investigated trends in the incidence of uterine cancer in Japan. Data from the Gynecological Cancer Registry of Niigata comprising all new cases of uterine cancer registered for the entire female population aged 15 years and over a 25-year period were examined. The age-standardized ratio of carcinoma in situ has substantially increased among females <40 years of age (from 3.8 (in the period of 1982-1989) to 40.9 (2000-2007). There was a significant trend in increasing incidence of invasive cervical cancer for those <40 years of age (from 4.7 to 13.1), whereas a significant trend of decreasing incidence for the 50+ year age group. The ratios of corpus cancer were increased approximately two-folds both among the population aged <50 years and those aged 50+ years and thus becoming equivalent to invasive cervical cancer. This prefecture-wide population-based study shows the practical trend in uterine cancer in Japanese females. The current health service must emphasize education among young adults concerning cervical cancer prevention while concentrating on screening. Avoiding risk factors, such as obesity, and increasing protective factors may lower risk for corpus cancer both in younger and older females.