An electroluminescent display device includes a display panel including a plurality of pixels each including a light-emitting element, a display brightness value adjuster configured to output brightness data with different values according to user inputs to adjust screen luminance of the display panel, a duty adjuster configured to adjust an emission duty of the light-emitting element according to the brightness data, and a power adjuster configured to adjust a low-level source voltage to be applied to the pixels within a preset power supply voltage range according to the brightness data, wherein the emission duty of the light-emitting element gradually increases from 0% to an upper limit set to be less than 100%.