Bismuth has been successfully introduced into the Sm-Ba-Cu-O system. X-ray powder diffraction patterns show that Sm_<1-x>Bi_xBa_2Cu_3O_y samples with x=0.1, 0.2, which were prepared by sintering, consist of two phases: the main phase has the orthorhombic perovskite-like structure reported for the high-Tc superconductor YBa_2Cu_3O_<7-δ> and the impurity phase is identified with BaCuO_2. It is found that the x-dependences of the lattice parameters are very similar to those for Sm_<1+x>Ba_<2-x>Cu_3O_<7-δ> or Eu_<1+x>Ba_<2-x>CO_<7-δ>. These results indicate that the Ba sites in the main phase are partly occupied by Bi^<3+> or Sm^<3+> ions.