The present invention is directed to a flat panel display whose brightness is adjusted based on inputted signals. In the flat panel display of the present invention, the pixels of the display panel are formed with capacitors for temporarily storing voltages corresponding to signals applied to the data lines responding to the scan signals applied to the scan lines and the pictures are displayed based on the voltages stored in the capacitors. Also, the display period controller controls a first period for storing a first voltage corresponding to a gray level of a picture to be displayed in the capacitors during one frame and a second period for storing a second voltage representing a black level in the capacitors, depending on a first signal representing a brightness level. Accordingly, the brightness of a variety of levels can be expressed without having to adjust a level of data voltage.