In a bottom gate type semiconductor device made of a semiconductor layer with crystal structure, source/drain regions are constructed by a lamination layer structure including a first conductive layer (n⁺ layer), a second conductive layer (n^-; layer) having resistance higher than the first conductive layer, and an intrinsic or substantially intrinsic semiconductor layer (i layer). At this time, the n^-; layer acts as LDD region, and the i layer acts as an offset region is a film thickness direction.