Disclosed are a digital broadcast receiver and a method for processing caption thereof. The digital broadcast receiver includes a demultiplexer for dividing a received MPEG-2 transmission stream into video data, audio data, supplementary information including EIT and PMI, wherein EIT or PMI contains caption service descriptor; a controller for decoding the caption service descriptor which indicates that digital hidden caption service or analog hidden caption service is contained in the video data according to Electronic Industries Association EIA708, the caption service number indicates the caption service number of the digital caption, and width-height ratio information indicates whether the caption data is suitable for a screen which width-height ratio is 16:9; and a caption decoder for decoding caption data from the user data of the video data.