Abstract. We introduce a method for volumetric cardiac motion analysis using variational optical flow computation involving the prior with the fractional order differentiations. The order of the differentiation of the prior controls the continuity class of the solution. Fractional differentiations is a typical tool for edge detection of images. As a sequel of image analysis by fractional differentiation, we apply the theory of fractional differentiation to a temporal image sequence analysis. Using the fractional order differentiations, we can estimate the orders of local continuities of optical flow vectors. Therefore, we can obtain the optical flow vector with the optimal continuity at each point.