For the purpose of improving efficiency in diagnosis by performing image reconstruction for slice planes lying at the same position in a subject both in a forward direction FD and backward direction BD, an amount of positional offset ‘dz’ is acquired, which amount represents a difference in a body axis direction ‘z’ along the forward direction FD and backward direction BD between a first subject position and a second subject position, the first subject position being a position to which a region to be imaged in the subject laid on a cradle 401 is moved when the cradle 401 is moved in the forward direction FD, and the second subject position being a position to which the region to be imaged in the subject laid on the moving cradle 401 is moved when the cradle 401 is moved in the backward direction BD such that the region to be imaged in the subject coincides with the first subject position. Then, respective pixel positions in the forward-path image and backward-path image are corrected based on the amount of positional offset ‘dz’ such that the pixel positions lie at positions corresponding to each other in the body axis direction ‘z’ along the forward direction FD and backward direction BD.