With a decoding method for decoding an encoded stream using a predetermined storage region where input of reproduction information indicating an reproduction state of the encoded stream is received, reference picture information indicating a reference picture necessary for performing decoding processing of a relevant picture in the encoded stream is obtained, based on the reproduction information input by the reproduction information input processing, whether the reference picture is stored in a predetermined storage region is determined, based on the reference picture information obtained by the reference picture information obtaining processing, the reference picture not stored in the storage region is obtained from the encoded stream and decoded, and storage thereof to the storage region is controlled, and the reference picture stored in the storage region is used to perform decoding processing of the relevant picture in the encoded stream, thereby generating image data which is stored in the storage region.