A silicon carbide semiconductor device includes a substrate, a drift layer located on a first surface of the substrate, a base region located on the drift layer, a source region located on the base region, a trench sandwiched by each of the base region to the drift layer, a channel layer located in the trench, a gate insulating layer located on the channel layer, a gate electrode located on the gate insulating layer, a source electrode electrically coupled with the source region and the base region, a drain electrode located on a second surface of the substrate, and a deep layer located under the base region and extending to a depth deeper than the trench. The deep layer is formed into a lattice pattern.