In decoding code data encoded in object units, decoders corresponding to the number of objects are needed. However, it is impossible to always provide a sufficient number of decoder. Accordingly, when code data 8 is decoded, an object combiner 43 refers to the number s of objects included in the code data 8, detected by an object counter 41, and the number d of object decoders, detected by an object decoder counter 42. If s>d holds, the object combiner 43 regulates the number of the objects of the input code data 8 to d.