A manufacturing process of an LCD device of the invention includes forming a first substrate provided with a pixel part with thin film transistors and a seal portion arranged around the pixel part, forming a second substrate opposed to the first substrate, filling a liquid crystal layer between the first substrate and the second substrate, and adhering the first substrate to the second substrate with a sealant provided for the seal portion, wherein the forming the first substrate includes forming a semiconductor layer composing the thin film transistor, forming in the seal portion a semiconductor connection layer made of a same material as the semiconductor layer, and forming an organic interlayer insulating film, wherein the forming the semiconductor layer and the forming the semiconductor connection layer are performed in the same step.