A semiconductor device has an active region defined by a device isolation region arranged on a surface of a semiconductor substrate, a plurality of transistor pillars arranged along a first direction within the active region, and a first dummy pillar disposed in the device isolation region. The first dummy pillar is arranged on a line extending along the first direction from the transistor pillars. The semiconductor device also has a second dummy pillar disposed between the transistor pillars and the first dummy pillar, a gate electrode continuously extending so as to surround each of side surfaces of the transistor pillars, a first power supply gate electrode surrounding a side surface of the first dummy pillar, and a second power supply gate electrode surrounding a side surface of the second dummy pillar. The second power supply gate electrode is connected to the gate electrode and the first power supply gate electrode.