When the settings of the region of interest are received from the operator, the measurement data acquisition control unit performs control so that an image for generating profile data is taken, and the data processing unit generates profile data in the encoding directions of the set region of interest. Then, the field-of-view setting unit sets the field of view in each of the encoding directions, based on the relationship between the dimensions of the subject P in the encoding directions that are calculated from the profile data of the encoding directions and the dimensions of the region of interest in the corresponding encoding directions, by use of coefficients stored in the coefficient storage unit.