To provide a semiconductor device having lower junction capacitance, which can be manufactured with lower power consumption through a simpler process as compared with conventional, a semiconductor device includes a base substrate; a semiconductor film formed over the base substrate; a gate insulating film formed over the semiconductor film; and an electrode formed over the gate insulating film. The semiconductor film has a channel formation region which overlaps with the electrode with the gate insulating film interposed therebetween, a cavity is formed between a recess included in the semiconductor film and the base substrate, and the channel formation region is in contact with the cavity on the recess.