When VC inspection for a TEG is performed, it is easily detected whether any failure of a contact plug occurs or not by increasing an emission intensity of a contact plug, so that reliability of a semiconductor device is improved. An element structure of an SRAM is formed on an SOI substrate in a chip region. Also, in a TEG region, an element structure of an SRAM in which a contact plug is connected to a semiconductor substrate is formed on the semiconductor substrate exposed from an SOI layer and a BOX film as a TEG used for the VC inspection.