A video encoding method using fractional-accuracy motion compensation, the method comprising: a step of performing motion searches to acquire motion vectors; a step of calculating reference probabilities at fractional-pixel positions based on their rate of designation by the acquired motion vectors; a step of dividing interpolation positions which are the fractional-pixel positions into multiple groups based on the calculated reference probabilities; a step of selecting, for each of the groups of the interpolation positions, interpolation filter coefficients to be used for generating an interpolated prediction picture from among multiple interpolation filter coefficient candidates; a step of generating the interpolated prediction picture using the selected interpolation filter coefficients and performing encoding with the fractional-accuracy motion compensation based on the interpolated prediction picture, for each of the groups of the interpolation positions; and a step of encoding information indicating grouping of the interpolation positions and information indicating interpolation filter coefficients to be used for each of the groups of the interpolation positions, wherein in selection of the interpolation filter coefficients, a degree of importance is set based on the reference probabilities under an assumption that the higher a reference probability is, the higher the degree of importance of a group of interpolation positions is, and interpolation filter coefficients or a candidate for the interpolation filter coefficients corresponding to an interpolation filter having a larger shape, a longer filter length, or a larger bit depth as the degree of importance becomes higher are selected based on the set degree of importance. a step of performing motion searches to acquire motion vectors; a step of calculating reference probabilities at fractional-pixel positions based on their rate of designation by the acquired motion vectors; a step of dividing interpolation positions which are the fractional-pixel positions into multiple groups based on the calculated reference probabilities; a step of selecting, for each of the groups of the interpolation positions, interpolation filter coefficients to be used for generating an interpolated prediction picture from among multiple interpolation filter coefficient candidates; a step of generating the interpolated prediction picture using the selected interpolation filter coefficients and performing encoding with the fractional-accuracy motion compensation based on the interpolated prediction picture, for each of the groups of the interpolation positions; and a step of encoding information indicating grouping of the interpolation positions and information indicating interpolation filter coefficients to be used for each of the groups of the interpolation positions, wherein in selection of the interpolation filter coefficients, a degree of importance is set based on the reference probabilities under an assumption that the higher a reference probability is, the higher the degree of importance of a group of interpolation positions is, and interpolation filter coefficients or a candidate for the interpolation filter coefficients corresponding to an interpolation filter having a larger shape, a longer filter length, or a larger bit depth as the degree of importance becomes higher are selected based on the set degree of importance.