A spin transistor conducive to the miniaturization and large scale integration of devices, because a magnetization direction of a source and a drain is determined by a direction of the epitaxial growth of a ferromagnet. The spin transistor includes a semiconductor substrate having a channel layer formed thereinside; ferromagnetic source and drain epitaxially grown on the semiconductor substrate and magnetized in a longitudinal direction of the channel layer due to magnetocrystalline anisotropy—the source and drain being disposed spaced apart from each other in a channel direction and magnetized in the same direction—; and a gate disposed between the source and the drain to be insulated with the semiconductor substrate and formed on the semiconductor substrate to control the spin of electrons that are passed through the channel layer.