In a semiconductor device, a body thick film transistor and a body thin film transistor having a different body film thickness are formed on the same SOI substrate (silicon support substrate, buried oxide film and silicon layer). The body film is formed to be relatively thick in the body thick film transistor, which has a recess structure where the level of the surface of the source/drain regions is lower than the level of the surface of the body region, and thus, the SOI film in the source/drain regions is formed to be as thin as the SOI film in the body thin film transistor. On the other hand, the entirety of the SOI film is formed to have a relatively thin film thickness in the body thin film transistor. In addition, the source/drain regions are formed to penetrate through the silicon layer.