We have studied crystal structures of europium C-60 compounds by high resolution x-ray diffraction measurements. In the systematic synthesis of EuxC60 for x (0 less than or equal to x less than or equal to 6), two stable phases appear at x = 3 and 6. Eu6C60 has a bce structure, which is an isostructure to M6C60 (M represents an alkali or alkaline earth metal). Eu3C60 has a superstructure derived by doubling the fcc pristine C-60 crystal along three principal axes. This superstructure comes from an ordering of cation vacancies, which is analogous to Yb2.75C60.