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 includes at least two luminance adjusting units enabled in response to a user input through a user interface and reduces a luminance of an APL section equal to or less than a predetermined reference value, a data modulator modulating data of the input image using a luminance defined in the APL curve data, 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.