A semiconductor device (10) of the present invention includes: a drift layer (5) that includes a reference concentration layer (4) including an impurity of a first conductive type at a first reference concentration and a low concentration layer (3) provided under the reference concentration layer and including an impurity of the first conductive type at a concentration lower than the first reference concentration; a gate electrode (20) that is formed on an upper surface of the reference concentration layer; a pair of source regions (Sa and 8b) that are respectively provided on the reference concentration layer in the vicinity of ends of the gate electrode and include an impurity of the first conductive type at a concentration higher than the first reference concentration.