Liquid Li-Pb eutectic alloy and lithium, assumed to be used in a liquid blanket system for fusion reactors, can easily contain light element impurities. It is thought that these impurities have bad influences on compatibility with structural materials. However, an effective reducing method for impurities has not yet been established. In this work, an electrochemical method is focused on this application. The experimental results of our work suggest the transfer of hydrogen and nitrogen impurities. From the results, a possible way to remove the impurities by electrochemical method is shown.