1. A magnetic resonance imaging system comprising: magnetic field generating means for generating a static magnetic field, a gradient magnetic field, and a selective excitation pulse, to be applied to an object being examined; excitation means for causing said magnetic field generating means to apply the static magnetic field, the gradient magnetic field, and the excitation pulse to the object being examined, at a predetermined timing, thereby selectively exciting a magnetic resonance phenomenon in a specific slice of the object being examined; excitation control means including means for causing said excitation means to excite a certain slice of the object being examined, and then causing said excitation means to excite a next successive, non-contiguous slice, separated from said certain slice by at least the thickness of a single slice, said next successive, non-contiguous slice excited subsequently by the selective excitation pulse with a corresponding magnetic gradient, within an excitation-repeating time of the slice, said excitation control means controlling said excitation means so as to excite a plurality of contiguous slices; resonance data acquisition means for detecting a magnetic resonance signal induced by magnetic resonance excited by said excitation control means, to acquire data relating to resonance; and image generating means for generating a magnetic resonance image on the basis of the resonance data acquired by said resonance data acquisition means.