1. A magnetic resonance imaging system for obtaining an MR image of an object by scanning a region of the object previously located on a positioning image previously acquired from the object, the system comprising: a displaying unit configured to display 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; an inputting unit configured to enable information about a running state of the target in a direction along the target to be supplied toward each of the tomographic images; an approximating unit configured to calculate 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; and a locating unit configured to locate the region substantially perpendicular to the approximated curve.