Wayside Energy Storage Systems (WESSs) are studied for energy saving of railway system. To maximize the energy saving effect of WESSs, a power control strategy which realize higher charge/discharge power is necessary. Currently, Current Based Control, which regulates current of ESDs, and Voltage Based Control, which regulates DC input voltage are generally applied. However, the difference of the dynamic characteristics between Voltage Based Control and Current Based Control has not discussed before. The aim of this paper is to compare the dynamic characteristics of Voltage Based Control and Current Based Control. First of all, a theoretical analysis on dynamic characteristics of both control strategies is carried out. This analysis revealed the maximum limitation of a control gain, which has an impact on the energy saving, for each control strategy. Utilizing these maximum control gain, an analysis on the static characteristics is performed to verify the energy saving effect for each control strategy. As a result, an advantage of Voltage Based Control is verified from the viewpoint of contribution to energy saving in DC-electrified railway system.