Eu2Mn2/3Ta4/3O7 specimen was synthesized from Eu2O3, MnO and Ta2O5 in a reducing atmosphere. Structure analysis was carried out by Rietveld method from X-ray diffraction data. The X-ray diffraction profile calculated with monoclinic C2/c model was in a good agreement with the observed X-ray diffraction patterns since several small peaks of super lattice could be also assigned with C2/c symmetry in addition to fundamental reflection peaks. Eu2Mn2/3Ta4/3O7 has two kinds of distorted(Mn, Ta)O6 octahedra and HTB layers, which deviates from the regular forms. Europium atoms coordinate to eight or seven oxygen atoms and lead to two kinds of polyhedra, EuO8 and EuO7 in this compound.