A decoding method for decoding plural pictures constituting a moving image from a bit stream, the decoding method comprising: a first and second information extracting step of extracting, from the bit stream on a picture-by-picture basis, either of (i) first information indicating that a target picture, which is one of an I picture, a P picture, and B picture, can be a reference picture to be referred to when decoding at least one of P pictures following the target picture or decoding at least one of B pictures following the target picture and (ii) second information indicating that the target picture cannot be a reference picture to be referred to when decoding each of P pictures following the target picture or decoding each of B pictures following the target picture; a third information extracting step of extracting, from the bit stream on a picture-by-picture basis, (iii) third information indicating a plurality of candidate reference pictures, the candidate reference picture being a candidate for a reference picture selected from among pictures for which only the first information is attached, when decoding a target P picture or decoding a target B picture; a fourth information extracting step of extracting, from the bit stream on a block-by-block basis, (iv) fourth information indicating one specified reference picture to be referred to when performing predictive decoding on a target block included in the target P picture or indicating one or two specified reference pictures to be referred to when performing predictive decoding on a target block included in the target B picture; a storing step of storing, on a picture-by-picture basis, the target picture into a memory as a candidate reference picture only when the first information is extracted by the first and second information extracting step; and a decoding step of decoding, on a block-by-block basis, the target block by using the one specified reference picture when performing predictive decoding on the target block included in the target P picture or by using the one or two specified reference pictures to be referred to when performing predictive decoding on the target block included in the target B picture, wherein said one specified reference picture is specified on a block-by-block basis, from among a plurality of candidate reference pictures which are stored in the memory, and the target block is predictively decoded with reference to the one specified reference picture when performing predictive decoding on the target block included in the target P picture, and wherein said one or two specified reference pictures are specified, on a block-by-block basis, from among a plurality of candidate reference pictures which are stored in the memory, and the target block is predictively decoded with reference to the one or two specified reference pictures when performing predictive decoding on the target block included in the target B picture. a first and second information extracting step of extracting, from the bit stream on a picture-by-picture basis, either of (i) first information indicating that a target picture, which is one of an I picture, a P picture, and B picture, can be a reference picture to be referred to when decoding at least one of P pictures following the target picture or decoding at least one of B pictures following the target picture and (ii) second information indicating that the target picture cannot be a reference picture to be referred to when decoding each of P pictures following the target picture or decoding each of B pictures following the target picture; a third information extracting step of extracting, from the bit stream on a picture-by-picture basis, (iii) third information indicating a plurality of candidate reference pictures, the candidate reference picture being a candidate for a reference picture selected from among pictures for which only the first information is attached, when decoding a target P picture or decoding a target B picture; a fourth information extracting step of extracting, from the bit stream on a block-by-block basis, (iv) fourth information indicating one specified reference picture to be referred to when performing predictive decoding on a target block included in the target P picture or indicating one or two specified reference pictures to be referred to when performing predictive decoding on a target block included in the target B picture; a storing step of storing, on a picture-by-picture basis, the target picture into a memory as a candidate reference picture only when the first information is extracted by the first and second information extracting step; and a decoding step of decoding, on a block-by-block basis, the target block by using the one specified reference picture when performing predictive decoding on the target block included in the target P picture or by using the one or two specified reference pictures to be referred to when performing predictive decoding on the target block included in the target B picture,