A display device and a method for controlling a luminance of the display device are disclosed. The display device includes an average picture level (APL) calculator which calculates an APL of an input image and outputs the APL of the input image and an APL curve data, a luminance adjuster which adjusts the APL curve data and includes at least two luminance adjusting units which are enabled in response to a user input through a user interface, a data modulator for modulating data of the input image using a luminance defined in the APL curve data adjusted by the luminance adjuster, and a display panel driving circuit which writes data from the data modulator on a display panel and reproduces the input image on the display panel.