Nissan Motor Co., Ltd, has delivered the New X-TRAIL FCV 2005 Year Model to customers in April 2006 in Japan, in which a newly developed in-house fuel cell stack and 70-MPa high-pressure hydrogen storage system are installed. For fuel cell vehicles, not only the fuel cell system and the hydrogen storage system but also the high-voltage system is very important, such as a traction motor to propel the vehicle, motors that drive some devices for the fuel cell system, a second battery that stores braking energy and assists the acceleration, inverters which supply alternating current to the prescribed motors, and converters which change voltage generated by the fuel cell stack to the specific level for each subsystems to operate. X-TRAIL FCV 2005MY has increased the performance of driving range and acceleration compared to 2003MY. We have practiced using new technologies to reduce the size reduction of the high-voltage system to achieve these performance improvements, but it still needs many improvements to make fuel cell vehicles popular to the market