A curved and flat combined display device includes a display panel having a flat area and a curved area, a compensation value generator configured to compare curved area data of an image data input from an external system with curved area data of imaged data generated by capturing the display panel, and generate compensation value data for the curved area of the display panel, based on the comparing result, and a controller configured to compensate for the curved area data of the image data input from the external system based on the compensation value data, and control the display panel to display the compensated curved area data of the image data.