Semiconductor device with backside N-type layer at active region/termination region boundary and extending into action region

A p type anode layer is formed on a front surface of an n type drift layer in an active region. An n type buffer layer is formed on a rear surface of the n− type drift layer. An n type cathode layer and a p type cathode layer are formed side by side on a rear surface of the n type buffer layer. An n type layer is formed on the rear surface of the n type buffer layer in a boundary region between the active region and the terminal region side by side with the n type cathode layer and the p type cathode layer. An extending distance of the n type layer to the active region side with an end portion of the active region as a starting point is represented by WGR1, and WGR1 satisfies 10 μm≤WGR1≤500 μm.