In the case of depositing a metal in a plurality of stages by applying deposition voltages having a plurality of rectangular waves at different voltages to an electrochemical display element, the application time of the rectangular wave at the highest voltage among the plurality of rectangular waves is set to a time (Tip) required for reaching a resistance inflexion point (Rip) where the resistance value (R) of a pixel starts to rapidly increase or shorter. Thus, the element can be prevented from being broken without deteriorating the response characteristics of a display element.