To decode coded pictures each of which has dependencies within the picture, using conventional decoding circuits and without deteriorating the efficiency in parallel processing.An image decoding device (100) includes: a stream segmentation unit (110) which segments a bit stream such that each of the coded pictures are segmented into two areas; and decoding processing units (120, 130) each of which decodes a corresponding one of the two segmented bit streams. The respective decoding processing units (120, 130) include: decoding units (123, 133) each of which generates decoded data including pixel data and control data; transfer determination units (124, 134) each of which determines whether or not the decoded data is referred to in another one of the processing units; data transfer units (125, 135) each of which transfers decoded data to the other processing unit; and decoding determination units (122, 132) each of which determines whether or not the decoded data to be referred to has been obtained. Each of the decoding units (123, 133) decodes a corresponding one of the segmented bit streams when reference decoded data has been obtained.