A moving picture coding apparatus, method, and medium for coding a current block are provided. A first candidate is derived from a first motion vector that has been used to decode a first block. The first block is adjacent to the current block. A first index identifying a reference picture to be selected for coding the current block is coded. A second candidate having a second motion vector that includes a non-zero value is derived. The non-zero value is assigned to the reference picture. A selected candidate is selected from a plurality of candidates, including the first candidate and the second candidate. A second index identifying the selected candidate is coded. The current block is coded using the selected candidate. The second candidate includes the non-zero value of the reference picture, with the reference picture being selected from a plurality of referable reference pictures.