An image decoding device capable of performing parallel decoding of coded image data with a small memory bandwidth while suppressing momentary increase in the amount of data transferred for the decoding. An image decoding device (100) includes: an external memory (110) which stores data of reference images; a stream parser unit (120) which decodes reference information indicating the number of reference images to be referred to on a block-by-block basis; an amount-of-transferred-data prediction unit (131) which calculates, on a block-by-block basis using the reference information, a predictive data amount of a reference image to be read out from the external memory (110); a block determination unit (132) which determines, using the predictive data amount, multiple blocks to be decoded in parallel, so as to reduce variation in amounts of data read out from the external memory (110); and macroblock decoding units (140 to 160) which decode the determined blocks in parallel.