A decoding apparatus for decoding two encoded field data obtained by hierarchically encoding two field data associated with each of a plurality of picture data composing a moving picture image. The decoding apparatus comprising: a first decoding unit configured to decode one of the two encoded field data and obtain information associated with the two encoded field data; a conversion unit configured to interpolate first predicted image data generated by decoding by the first decoding unit according to the information and generate second predicted image data of a scanning position of the other encoded field data of the two encoded field data; and a second decoding unit configured to decode the other encoded field data of the two encoded field data based on the second predicted image data generated by the conversion unit.