1. A moving picture decoding method for decoding a current block, comprising: deriving a first candidate having a first motion vector predictor derived from a first motion vector that has been used to decode a first block; determining whether a total number of one or more candidates having the first candidate is less than a maximum candidate number; deriving a second candidate having a second motion vector predictor when the total number of the one or more candidates having the first candidate is less than the maximum candidate number, the second motion vector predictor being a zero vector; and decoding a coded index corresponding to a candidate having a motion vector predictor, wherein the maximum candidate number is used to decode the coded index, wherein a bitstream has the coded index, and wherein the candidate is one of a plurality of candidates having the first candidate and the second candidate.