An organic light emitting display device comprising: a source device configured to output image data; and a sink device configured to perform a displaying operation based on the image data, wherein the source device is configured to change a frame rate of an image frame composing the image data while the displaying operation is performed, wherein the sink device is configured to change a frame rate of a panel driving frame for the displaying operation as the frame rate of the image frame is changed, and wherein the source device is configured to change the frame rate of the image frame while satisfying a condition in which an emission duty ratio of the panel driving frame is not changed.