A semiconductor device includes a semiconductor element, a terminal electrode, and internal wiring. The semiconductor element is housed in a case. The terminal electrode is provided electrically connectable to an outside of the case. The internal wiring is provided in the case and electrically connects the semiconductor element and the terminal electrode. The internal wiring includes a fuse portion provided at a part of the internal wiring and configured to be melted by an overcurrent. The fuse portion includes a plurality of metal wires which are a group of parallel wires. Of the plurality of metal wires, a first metal wire is higher in resistance value than a second metal wire laid on an outer side relative to the first metal wire.