The electronic structures of the pyrochlore-type Ru oxides\hfil Sm_2-xCa_xRu₂O₇ and Sm_2-xBi_xRu₂O₇, which show metal--insulator transition with increasing Ca or Bi concentration, have been studied by ultraviolet photoemission spectroscopy. Spectral changes near the Fermi level are different but reflect the tendency of their transport properties in both systems. The Sm_2-xCa_xRu₂O₇ system shows an energy shift, which is expected from the increase of hole in the Ru 4d t_2g band and the Sm_2-xBi_xRu₂O₇ system shows spectral weight transfer within the Ru 4d t_2g band, which is expected to be observed in bandwidth-control Mott-Hubbard system.

PACS numbers: 71.30.+h, 71.27.+a, 71.28.+d, 79.60.--i