The organic light emitting display may include a plurality of pixels for generating light components with predetermined brightness components while controlling the amount of current that flows from a first power source to a second power source via organic light emitting diodes (OLED), a first power source controller for extracting data of the highest gray level among input data items of one frame and for outputting a control value having voltage information corresponding to the highest gray level data, and a first power source generator for generating a controlled voltage value corresponding to the control value and outputting the controlled voltage value to the first power source.