In a manufacturing step in which a structure of target of screening is formed on a semiconductor substrate in the middle of manufacturing process before a semiconductor device is finished, screening of potential defects of a gate insulating film is performed for each wafer at one time so that the semiconductor device is caused to appear as an initial defective product when the finished semiconductor device is subjected to an electrical characteristic test. Provided are a semiconductor device, and a method of manufacturing a semiconductor device which enables reliable screening of potential defects in a short period of time.