We have been studying the application of a permanent magnet synchronous motor (PMSM) for railway vehicle traction in order to reduce the weight and size of direct drive traction motors. As a part of this study, it is required to establish a current control system of PMSM suitable for railway vehicle traction. In this paper, we discuss the current control system mentioned above and suggest a method which is available under the condition of railway vehicle traction. Next we investigate how to decide the current response time constant T_d and reach a conclusion that about 10ms is appropriate under some assumed conditions. Then we check this current control system, when used for railway vehicle traction, through experiments and studies on influence of parameter changing and sudden changes in the line voltage. Finally we can conclude that the current control system has satisfactory performance for railway vehicle traction.