A magnetic resonance imaging system is provided for obtaining MR images by scanning a region of the object previously located on an object's positioning image. The system comprises a displaying unit, inputting unit, approximating unit, and locating unit. The displaying unit displays a plurality of tomographic images of the object as the positioning image, each of the tomographic images including an indication of a target of interest thereon. The inputting unit enables information about a running state of the target in a direction along the target to be supplied toward each of the tomographic images. The approximating unit calculates three-dimensionally an approximated curve indicating the running state of the target in the direction on the basis of the supplied information about the running state. The locating unit locates the region substantially perpendicular to the approximated curve.