AgX (X = Cl, Br, I) is prepared by the precipitation method. AgX can easily become Ag-AgX by the indoor sunlight due to its photosensitivity, especially in the case of AgCl and AgBr. In order to evaluate the effect from Ag-AgX, under the simulated sunlight illumination, photodegradation reactions of azo dyes (methyl orange and congo red) by Ag-AgX are performed. The photodegradation kinetics of azo dyes by Ag-AgCl or Ag-AgBr is rapid; however, the photodegradation kinetics of azo dyes by Ag-AgI is slow. We measure HO center dot generated from Ag-AgX systems and characterize Ag-AgX using different techniques. In this work, though, our focus is to elucidate that Ag-AgX can be decomposed irreversibly by the indoor sunlight, as well as by the simulated sunlight illumination. Therefore, we should not term Ag-AgX the photocatalyst, and we should not term the effect from Ag-AgX the photocatalysis.