A semiconductor device has a first transistor of a first conductivity type and a second transistor of a second conductivity type, the first transistor is arranged in an active region of a semiconductor substrate, and a gate electrode and the active region overlap with each other in a plan view and also have a portion located between the source and the drain of the first transistor of the semiconductor substrate. In the channel width direction, an impurity concentration of the second conductivity type is higher at the end than on the center side of the portion.