A vertical stack transistor includes: a first transistor and a second transistor, located in a vertical direction, wherein the first transistor includes a first gate electrode, a first insulating layer, a first electrode, a first channel, and a second electrode, which are sequentially stacked in the vertical direction, and the second transistor includes a second gate electrode, a second insulating layer, a third electrode, a second channel, and a fourth electrode, which are sequentially stacked in the vertical direction, wherein the second gate electrode and the second electrode are the same electrode.