The inhomogeneity in a congruent LiTaO3 crystal has been observed by transmission synchrotron topography. Many extraordinary regions exist in congruent LiTaO3 crystal and they often show diffraction intensity different from that of ordinary regions in synchrotron topographs. Differential thermal analysis indicates that the Curie temperature of the extraordinary region is lower than that of ordinary region, and the extraordinary region is really a high defect density region. The diffraction contrast of the extraordinary region in synchrotron topographs is explained qualitatively by a calculation at the selected wavelength.