To provide a decoding apparatus and decoding method capable of efficiently storing, in a memory, image data of which the bit width is made different according to a pixel position in an image.

A decoding apparatus includes an overlap processing unit which carries out smoothing processing in a first direction and smoothing processing in a second direction for a block boundary of an attention macro block to produce image data including a plurality of M pieces of first pixels each constituted of (m) bits and a plurality of N pieces of second pixels each constituted of (n) bits; and a bit number conversion unit which produces compressed data of mN bits by applying reversible compression processing to a set of data of nN bits aggregating the N pieces of second pixels. produces N pieces of divided data constituted of (m) bits by dividing the compressed data, and stores, in the memory, the image data of the M pieces of first pixels and the N pieces of divided data as data of (m) bits, respectively.