A semiconductor device includes a first conductive type first main electrode region, a first conductive type drift region which makes contact with the first main electrode region, a first conductive type second main electrode region which makes contact with the drift region, a second conductive type well region which is provided in a part of a surface layer portion of the drift region and to which a reference potential is applied, and a first conductive type potential extracting region which is provided in a surface layer portion of the well region and to which the reference potential is applied. The well region serves as a base region which controls a current flowing between the potential extracting region and the drift region. Thus, it is possible to provide a novel semiconductor device which is high in reliability while the increase of the chip size can be suppressed.