According to an embodiment a semiconductor device includes a semiconductor layer including first trenches and second trenches, a first gate electrode in the first trench, a second gate electrode in the second trench, a first gate electrode pad, a second gate electrode pad, a first wiring connecting the first gate electrode pad and the first gate electrode, and a second wiring connecting the second gate electrode pad and the second gate electrode. The semiconductor layer includes a first connection trench. Two first trenches adjacent to each other are connected to each other at end portions by the first connection trench. At least one of the second trenches is provided between the two first trenches. The second gate electrode in the at least one second trench is electrically connected to the second wiring between the two first trenches.