A motion vector encoding apparatus includes a detection unit for detecting motion vectors of respective blocks of a predetermined size and a range of the motion vectors; a first storage unit for storing therein the detected motion vectors; and a generation unit for generating motion vector predictors from the motion vectors outputted from the first storage unit. The apparatus also includes a calculation unit for calculating an average value of differential vectors between the motion vectors outputted from the first storage unit and the motion vector predictors. Moreover, the apparatus includes a determination unit for determining a parameter representing a motion vector encodable range based on the average value of the differential vectors calculated by the calculation unit; and an encoding unit for encoding the motion vectors based on the differential vectors and a parameter representing an encodable range outputted from the determination unit.