A semiconductor device has a silicon substrate, an external connection terminal disposed on the silicon substrate, an internal circuit region disposed on the silicon substrate, an NMOS transistor for electrostatic discharge protection provided between the external connection terminal and the internal circuit region, and a wiring connecting together the external connection terminal and the NMOS transistor and connecting together the NMOS transistor and the internal circuit region. The NMOS transistor has a drain region and a gate electrode whose potential is fixed to a ground potential. The external connection terminal is smaller than the drain region and is formed above the drain region.