An MR apparatus 1 comprising an image producing unit 101 for producing axial images D1 through D10; a binarizing unit 102 for executing binarization processing for binarizing the axial images; a separating unit 103 for executing separation processing for separating a left-arm region HL and a right-arm region HR from a torso region HB; an extracting unit 104 for executing extraction processing for extracting the torso region HB from the images obtained by the separating unit 103; and a unit for locating a centerline of a body of a subject by executing first removal processing on an extracted region HE2 extracted by the extraction processing, and locating a centerline of the body of the subject based on the first-removal-processed extracted region.