To provide an image decoding technology capable of decoding at high speed and to provide an image decoding technology that has high versatility of uses.

S, R, C pass decoding unit 12S can decode data of all passes included in coded image data. An R pass decoding unit 12R and a C pass decoding unit 12C can respectively decode data of R and C passes. A header information analyzing unit 104 interprets a header of the coded image data to analyze the data as to whether or not the data can be decoded in parallel. When the header information analyzing unit 104 discriminates that the parallel decoding is possible, the three decoding units, that is, the S, R, C pass decoding unit 12S, the R pass decoding unit 12R and the C pass decoding unit 12C decode data of the respective passes in parallel. The S, R, C pass decoding unit 12S decodes exclusively the data of the S pass. When it is discriminated that the parallel decoding is impossible, the S, R, C pass decoding unit 12S sequentially decode the data of all the passes.