An organic light-emitting display device can include a display panel including a plurality of pixels and configured to express luminance based on a driving current corresponding to a data signal for providing a data voltage and a first power; a control circuit configured to output a first mode control signal corresponding to a normal mode and a second mode control signal corresponding to a standby mode for providing lower luminance than the normal mode; and a power source configured to supply the first power to the display panel at a first voltage level, in response to receiving the first mode control signal corresponding to the normal mode, and supply the first power to the display panel at a second voltage level that is lower than the first voltage level, in response to receiving the second mode control signal corresponding to the standby mode.