A semiconductor device including a protection device and a protected device, the protection device includes a first semiconductor region of a second conductivity type formed over a substrate, a second semiconductor region of the second conductivity type provided in the first semiconductor region, having a higher impurity concentration than the first semiconductor region, a third semiconductor region of the second conductivity type formed in a surface layer of the second semiconductor region, having a higher impurity concentration than the second semiconductor region, a fourth semiconductor region of the second conductivity type formed in the first semiconductor region and located away from the third semiconductor region, having a higher impurity concentration than the first semiconductor region, a fifth semiconductor region of a first conductivity type formed in the first semiconductor region and electrically short-circuited with the fourth semiconductor region, and a sixth semiconductor region of the first conductivity type.