1. An encoding device comprising: an accuracy transform unit that transforms a motion vector with fractional pixel accuracy of an image into a motion vector with integer pixel accuracy for each of prediction directions for bidirectional prediction of the image; a predicted image formation unit that forms a predicted image of bidirectional prediction for the image on the basis of the motion vector with integer pixel accuracy transformed by the accuracy transform unit for each of the prediction directions; and an encoding unit that encodes the image in accordance with a recursively divided block structure by using the predicted image of the bidirectional prediction formed by the predicted image formation unit.