a thin film el element includes a pair of electrodes disposed oppositely each other , a pair of insulator layers disposed between the electrodes , at least one of the insulator layers consisting essentially of tantalum oxide and at least one oxide selected from the group consisting of yttrium oxide and tungsten oxide , and a luminous layer held between the insulator layers . the el element can be operated at high luminance with only a minimum low voltage required for such an operation . further , the el element makes long - lived , stable , etc . display devices . furthermore , the el element can be produced by a simplified manufacturing process .