A semiconductor device includes a substrate and a plurality of transistors arranged on the substrate in an array. The transistor includes a first electrode, a plurality of second electrodes, and a gate electrode. The second electrodes are arranged around the first electrode. The gate electrode is located between the first electrode and the second electrodes. The first electrode is a circle or polygon. The gate electrode is around the first electrode, and an edge of the gate electrode facing the first electrode has a shape corresponding to that of the first electrode.