To prevent a decode start timing from being delayed even in the case of compression-coded variable rate input data.

Moving picture experts group MPEG image code data stored in a code buffer memory 21 are read immediately to a controller 15 and fed to a byte/word conversion section 136. When MPEG image code data with an amount (1 word in this case) to be able to be decoded are stored in the code buffer memory 21, a byte/word conversion section 136 can index a variable length decoding VLD table of a VLD section 131, then a clock signal is supplied to the VLD section 131, an inverse quantization section 132 and an inverse discrete cosine transform section 133 to start decoding.