A semiconductor device includes a first pillar-shaped semiconductor layer and a gate insulating film around the first pillar-shaped semiconductor layer. A gate electrode is around the gate insulating film and a gate line is connected to the gate electrode. A first diffusion layer resides in an upper portion of the first pillar-shaped semiconductor layer and a second diffusion layer resides in a lower portion of the first pillar-shaped semiconductor layer. A memory device on the first diffusion layer includes a pillar-shaped phase-change layer and a reset gate insulating film surrounding the pillar-shaped phase-change layer. A reset gate surrounds the reset gate insulating film, where the reset gate functions as a heater, and the pillar-shaped phase-change layer and the reset gate are electrically insulated from each other.