A method for manufacturing a semiconductor device by a small number of processes and by a means with high usability of materials to have high-definition and a gate insulating with a high step coverage property is disclosed. According to the present invention, a method for manufacturing a semiconductor device comprises the steps of forming a plurality of first conductive layers over a substrate; forming a first insulating layer to fill the gaps of the plurality of the first conductive layers; forming a second insulating layer over the first insulating layer and the plurality of the first conductive layers; and forming a semiconductor region and a second conductive layer over the second insulating layer.