The anisotropic reflection spectra of K2AgI3 Rb2AgI3 and Rb2AgBr3 have been measured in the range from 4 to 26 eV using synchrotron radiation. The optical constants have been obtained through the Kramers-Kronig analysis. The characters of the band edge excitons of K2AgI3 and Rb2AgI3 are very similar to those of the alkali iodides. However, the perturbation calculation has indicated that the spin-orbit interaction scarcely affect the outline of the valence band structure of Rb2AgI3 and that no spin-orbit doublet appears in the absorption spectra. The anisotropic absorption due to the core excitons of K+ or Rb+ have been found around 20 or 17 eV, respectively. The prominent structures due to plasmons of valence electrons have been found at 10-12 eV in the energy loss spectra.