Semiconductor device

A semiconductor device comprising:

• a first conductive type semiconductor layer which has a principal surface;
• a second conductive type well region which demarcates an active region and an outer region on the principal surface and is formed in a surface layer portion of the principal surface and includes a first concentration portion high in impurity concentration on the active region side and includes a second concentration portion lower in impurity concentration than the first concentration portion on the outer region side;
• a second conductive type impurity region of the active region which is formed on a surface layer portion of the principal surface;
• and
• a principal surface electrode directly connected to the second concentration portion, with neither the first concentration portion nor the impurity region interposed in between, wherein
• the well region demarcates the active region in an internal portion of the semiconductor layer and demarcates the outer region in a peripheral edge portion of the semiconductor layer in plan view and is also formed in an annular shape which surrounds the internal portion of the semiconductor layer,
• the first concentration portion is formed in an annular shape which surrounds the internal portion of the semiconductor layer in plan view, and
• the second concentration portion is formed in an annular shape which surrounds the first concentration portion in plan view.