This paper presents the development of a traction system for high-speed trains by adopting SiC power devices to pursue weight reduction and compactness of the system. We found that the combination of the SiC applied conversion system with a blower-less cooling system and 6-pole induction motors is a suitable approach to highlight the merits of SiC devices. The running tests of a prototype were conducted to confirm its sound performances. The developed traction system is installed in the latest type of Shinkansen train, or the Series N700S, which debuted in March 2018 and will enter commercial service in the summer of 2020. This SiC application to the high-speed train's traction system is the first in the world.