To manufacture a micro structure and an electric circuit included in a micro electro mechanical device over the same insulating surface in the same step. In the micro electro mechanical device, an electric circuit including a transistor and a micro structure are integrated over a substrate having an insulating surface. The micro structure includes a structural layer having the same stacked-layer structure as a layered product of a gate insulating layer of the transistor and a semiconductor layer provided over the gate insulating layer. That is, the structural layer includes a layer formed of the same insulating film as the gate insulating layer and a layer formed of the same semiconductor film as the semiconductor layer of the transistor. Further, the micro structure is manufactured by using each of conductive layers used for a gate electrode, a source electrode, and a drain electrode of the transistor as a sacrificial layer.