An image decoding apparatus includes a syntax-element compressing unit that executes compression processing on syntax elements extracted in syntax analysis processing and classifies the syntax elements based on types thereof, a plurality of syntax-element expanding units that correspond to any one of classified groups of syntax elements in a one to one relation and expand the syntax elements belonging to the corresponding group to restore the original syntax elements, and a plurality of signal processing units that correspond to any one of the syntax-element expanding units in a one to one relation and apply, to the syntax elements restored by the corresponding syntax-element expanding unit, signal processing corresponding to a type thereof.