According to one embodiment, a semiconductor device includes a semiconductor portion, a gate electrode, a source electrode, a first structure body, and a first insulating portion. The semiconductor portion includes SiC and includes first to third semiconductor regions. The first semiconductor region includes first to third partial regions. The second partial region is provided between the third partial region and the first partial region. The third semiconductor region is provided between the second partial region and the second semiconductor region. The source electrode is electrically connected to the second semiconductor region. The first insulating portion includes a first insulating region and a second insulating region. The first insulating region is provided between the first partial region and the gate electrode. The second insulating region is provided between the second semiconductor region and the first structure body. The first structure body includes at least one of polysilicon or TiN.