A semiconductor device according to one embodiment includes a semiconductor substrate having a first surface, an insulating isolation film disposed at the first surface, and a gate electrode. The semiconductor substrate has a source region, a drain region, a drift region, and a body region. The insulating isolation film has a first portion disposed inside the drift region in plan view, a second portion protruding from the first portion in a direction toward the source region, and a third portion protruding from the first portion in the direction toward the source region and sandwiching the drift region between the second portion and the third portion. The gate electrode faces a portion of the body region sandwiched between the source region and the drift region with being insulated from the portion. The gate electrode is disposed so as to extend over the second portion and the third portion.