When a digital broadcast receiver selects a channel and thereby changes an MPEG picture stream, a video decoder starts a decoding operation in response to an instruction to start decoding. When a predictive coded picture includes an intra slice and an intra macroblock, the video decoder decodes the intra slice and the intra macroblock of the predictive coded picture without waiting for an intra picture to be decoded. When a macroblock to be referred to has previously been decoded, the video decoder further decodes a non-intra slice and a non-intra macroblock of the predictive coded picture by using a decoding result of the macroblock to be referred to. Thus, when changing the channel, for example, it is possible to quickly obtain output picture data, shorten interruption of the pictures, and check a picture of the next channel in a short time.