A semiconductor device includes a semiconductor layer formed on an insulating layer; a gate electrode disposed on said semiconductor layer via a gate insulating film; a source/drain layer composed by including an alloy layer or a metal layer with a bottom surface in contact with the insulating layer, with joint surfaces to a channel region disposed along crystal orientation faces of said semiconductor layer; and impurity-doped layers formed in a self-aligned manner along interfaces of the alloy layer or the metal layer, and said semiconductor layer.