A memory device, an operating method of the memory device, and a fabricating method of the memory device are provided. A memory device includes: a semiconductor column extending vertically on a substrate and including a source region of a first conductivity type, an intrinsic region, and a drain region of a second conductivity type; a first gate electrode disposed adjacent to the drain region to cover the intrinsic region; a second gate electrode spaced apart from the first gate electrode and disposed adjacent to the source region to cover the intrinsic region; a first gate electrode disposed between the first gate electrode and the intrinsic region; and a second gate insulating layer disposed between the second gate electrode and the intrinsic region.