A spin transistor useful for device miniaturization and high-density integration is provided. The spin transistor includes: a semiconductor substrate including a channel layer; ferromagnetic source and drain disposed on the semiconductor substrate to be separated from each other and to be magnetized in a direction perpendicular to a surface of the channel layer; a gate formed on the semiconductor substrate between the source and the drain to adjust spins of electrons passing through the channel layer, wherein spin-polarized electrons are injected from the source to the channel layer, and the electrons injected into the channel layer pass though the channel layer and are injected into the drain, and wherein the spins of the electrons passing through the channel layer undergo precession due to a spin-orbit coupling induced magnetic field according to a voltage of the gate.