A semiconductor device includes a semiconductor part, first to third electrodes, and first and second control electrodes. The semiconductor part is provided between the first and second electrodes. On the second electrode side of the semiconductor part, the first control electrode and the third electrode are provided in a first trench, and the second control electrode is provided in a second trench. The first control electrode is provided between the second and third electrode. In a first direction from the first control electrode toward the second control electrode, the first trench has first and second widths. The first width is a combined width of the third electrode and insulating portions provided on both sides of the third electrode. The second width is a combined width of the first control electrode and the gate insulating films on both sides thereof. The first width is greater than the second width.