Endometrial carcinoma (EMC) is associated with obesity; however, the underlying mechanisms have not yet been elucidated. Peroxisome proliferator-activated receptor alpha (PPARα) is a nuclear receptor that is involved in lipid, glucose, and energy metabolism. PPARα reportedly functions as a tumor suppressor through its effects on lipid metabolism; however, the involvement of PPARα in the development of EMC remains unclear. The present study demonstrated that the immunohistochemical expression of nuclear PPARα was lower in EMC than in normal endometrial tissues, suggesting the tumor suppressive nature of PPARα. A treatment with the PPARα activator, irbesartan, inhibited the EMC cell lines, Ishikawa and HEC1A, by down-regulating sterol regulatory element-binding protein 1 (SREBP1) and fatty acid synthase (FAS) and up-regulating the tumor suppressor genes p21 and p27, antioxidant enzymes, and AT-rich interaction domain 1A (ARID1A). These results indicate the potential of the activation of PPARα as a novel therapeutic approach against EMC.