A semiconductor device with high reliability is provided using an SOI substrate. When the SOI substrate is fabricated by using a technique typified by SIMOX, ELTRAN, or Smart-Cut, a single crystal semiconductor substrate having a main surface (crystal face) of a {110} plane is used. In such an SOI substrate, adhesion between a buried insulating layer as an under layer and a single crystal silicon layer is high, and it becomes possible to realize a semiconductor device with high reliability.