Provided are a multi-gate MOS transistor and a method of manufacturing the same. Two silicon fins are vertically stacked on a silicon on insulator (SOI) substrate, and four side surfaces of an upper silicon fin and three side surfaces of a lower silicon fin are used as a channel. Therefore, a channel width is increased, so that current driving capability of a device is improved, and high performance nano-level semiconductor IC and highly integrated memory IC can be manufactured through the optimization and stability of a process.