Provided is a method for fabricating a nano-wire field effect transistor including steps of: preparing an SOI substrate having a (100) surface orientation, and nano-wire field effect transistor where two triangular columnar members configuring the nano-wires and being made of a silicon crystal layer are arranged one above the other on an SOI substrate having a (100) surface such a way that the ridge lines of the triangular columnar members face via an insulator; processing the silicon crystal configuring the SOI substrate into a standing plate-shaped member having a rectangular cross-section; and as a nanowire, processing the silicon crystal by orientation dependent wet etching into a shape where two triangular columnar members are arranged one above the other in such a way that the ridge lines of the triangular columnar members configuring the nano-wires face through the ridge lines thereof, and an integrated circuit including the nano-wire field effect transistor.