It is important for railway companies to reduce the power consumption of substations in order to reduce the contract power cost and facilities. This study proposes a decentralized control system for controlling the train power demand. Each train calculates its own power allocation independently and in parallel using the information broadcasted by the substations in this control scheme. This control system is very advantageous from the view point of communication load, plug & play' and capital investment because it does not need a server. This work investigates the effect of train power control using the decentralized control scheme via simple and precise numerical simulations' which demonstrate that several trains run on the railroad and are powered by a substation.