Photovoltaic characteristics have been studied for Ag-As-S cells which have coplanar electrodes consisting of Au or Ag films. When light irradiates only around one electrode, Au-electrode samples exhibit conventional photovoltages, while Ag-electrode samples show anomalous features; after illumination, dark voltages appear, which become greater than photovoltages. The observations seem to be related to photochemical Ag+ ionic reaction.