A moving picture coding apparatus includes: a motion vector predictor candidate calculation unit which calculates one or more motion vector predictor candidates and the number of available predictor candidates; an inter prediction control unit which selects an optimum motion vector predictor candidate; and a variable length coding unit which sets the motion vector predictor candidate list size to the number of available predictor candidates, and variable-length codes a motion vector predictor index used for coding a motion vector, by assigning a bit string according to the motion vector predictor candidate list size to the index.