Provided is a semiconductor device including at least two isolation trench portions; a mesa region that is provided between the at least two isolation trench portions and includes a source region having a first conduction type, a base region having a second conduction type and at least a portion thereof provided below the source region, and a gate trench portion; and a contact layer that is an epitaxial layer provided at least in contact with side portions of the mesa region and bottom portions of the isolation trench portions positioned lower than the gate trench portion, and having a second-conduction-type impurity concentration higher than that of the base region, wherein the same impurities as in the contact layer are present in the source region, or the contact layer is provided higher than the source region.