A semiconductor device includes a semiconductor base body, and a first main electrode and a second main electrode provided on the semiconductor base body. The semiconductor base body includes a drift region of a first conductivity type through which a main current flows, a column region of a second conductivity type arranged adjacent to the drift region in parallel to a current passage of the main current, a second electrode-connection region of the first conductivity type electrically connected to the second main electrode, and a low-density electric-field relaxation region of the first conductivity type having a lower impurity concentration than the drift region and arranged between the second electrode-connection region and the column region.