A high-definition image display device and a method of converting a frame rate thereof are provided. The high-definition image display device includes an image processing unit which processes an input image signal, a first frame rate conversion (FRC) unit which receives an image signal from the image processing unit and generates first interpolated data by processing a first part of frame data of the image signal, and a second FRC unit which generates second interpolated data by processing a second part of the frame data of the image signal and outputs the second interpolated data to the first FRC unit, wherein the first and second interpolated data are combined by and output from the first FRC unit. Accordingly, clear pictures can be provided by converting the frame rate through processing of large capacity data according to the high resolution of the image display device, using a plurality of FRC circuits.