To provide an image decoding apparatus capable of efficiently performing data transfer required at the time of decoding an encoded stream.

An execution pipeline is constituted of respective processing blocks for encoding images and respective processing blocks and an external memory for transferring data in each macro block are unitarily constituted to monitor an FIFO buffer 13 for a variable length decoding part 12. When the FIFO buffer 13 becomes empty, the processing of the variable length decoding part 12 is stopped, and after transferring data to the buffer 13 again, the processing is restarted to enable best-effort operation.