Rolling stocks are equipped with pneumatic brake system together with electric generation brake, which is a very important system for train safety. However, pneumatic brake system has such weak points as slower response and heavy weight. In order to improve them, we developed a hydraulic brake system with the following targets: quick response and small size, better utilization of adhesion, low price, higher reliability and less maintenance cost. The hydraulic brake system was estimated to have one-third weight of the conventional pneumatic brake system and to show quicker response than the conventional system does.