Interferometry of the nuclear Bragg scattered X-rays from (Fe2O3)-Fe-57 (777) with the optical path difference of 2.4 mm was reported. In order to carry out this measurement, a new X-ray interferometer of the wavefront-dividing type was designed and fabricated. The interference pattern was observed using this X-ray interferometer, since the temporal coherence length of the nuclear resonantly scattered X-rays is much longer than the optical path difference. From the visibility of the interference pattern, the vertical size of the X-ray source was estimated to be 50 mu m.