: Endometrial cancer is the most commonly diagnosed gynecological cancer and its incidence is increasing worldwide. The number of patients with this disease is likely to continue to grow, including younger patients. It is a complex disease driven by abnormal genetic and epigenetic alterations, as well as environmental factors. Many endometrial cancers show estrogen-dependent proliferation. The carcinogenic mechanisms are unknown or not completely explained beyond mutations of single oncogenes and tumor suppressor genes. Possible carcinogenic mechanisms include imbalance between endometrial proliferation by unopposed estrogen and the mismatch repair (MMR) system; rmethylation changes and mutation of genes. Epigenetic changes resulting in aberrant gene expression are dynamic and modifiable features of many cancer types. A significant epigenetic change is aberrant DNA methylation. In this review, we review evidence on the role of different changes in relation to endometrial carcinogenesis. Carcinogenic mechanisms of endometrial cancer involve both genetic and epigenetic changes. Determination of the detailed carcinogenic mechanisms will be useful for prevention and diagnosis of endometrial cancer, risk assessment, and development of new treatment strategies targeting genes.