Disclosed is a speed-change playback apparatus of a digital TV which performs better fast forward and backward performances by analyzing a transport stream inputted at the time of a time shift service and a method thereof. An MPEG decoder detects I picture location information in a TP packet by analyzing a TP packet inputted at the time of a time shift service, and a time shift software module extracts a TP packet constituting the I picture from the stored TP packets by the detected I picture location information and feeds to the MPEG decoder. Therefore, fast forward and fast backward performances can be efficiently performed by adding a simple logic which analyzes the TP packet to the MPEG decoder.