An encoding method according to an embodiment includes a deriving step and an encoding step. The driving step derives a first reference value that is a reference value of a weighting factor based on fixed point precision representing roughness of the weighting factor that is used for making a motion-compensated prediction of a change in a pixel value by multiplying a reference image by the weighting factor. The encoding step encodes a first difference value that is a difference value between the weighting factor and the first reference value. The weighting factor is included in a range of predetermined bit precision having the first reference value at approximate center.