A liquid crystal display device includes a source device that outputs image data and a sink device that performs a displaying operation based on the image data. The source device changes a frame rate of an image frame composing the image data while the displaying operation is performed. The sink device changes a frame rate of a panel driving frame for the displaying operation by adjusting a vertical blank period of the panel driving frame as the frame rate of the image frame is changed. Here, the sink device adjusts a common voltage applied to a display panel included in the sink device during a display operation of an individual frame, in accordance with the frame rate of the panel driving frame.