We studied on the effects of added metallic elements in Ag-alloy layers in the indium–tin-oxide (ITO)/Ag-alloy/ITO transparent conductive multilayer system. The sheet resistance and the transmittance of the multilayer system were estimated from the resistivity and optical constants of Ag-alloy. From the estimation, the most promising Ag-alloys were selected for the transparent conductive multilayer system. The correlation between thickness of the Ag-alloy layer and electrical and optical properties of the multilayer system has been investigated. The effect of added metallic elements in Ag-alloys was also studied from the point of durability. After a humidity test and a heat treatment test, we examined the changes in the sheet resistance and the transmittance as well as the density of white dots in the ITO/Ag-alloy/ITO multilayer. The experimental results confirm that the added metallic elements in Ag-alloys improve the durability of the multilayer system: Pd–Cu and Pd enhance the thermal stability and Au improves the durability in a humid environment.