A method of manufacturing a vertical memory device includes forming alternating and repeating insulating interlayers and sacrificial layers on a substrate, the sacrificial layers including polysilicon or amorphous silicon, forming channel holes through the insulating interlayers and the sacrificial layers, forming channels in the channel holes, etching portions of the insulating interlayers and the sacrificial layers between adjacent channels to form openings, removing the sacrificial layers to form gaps between the insulating interlayers, and forming gate lines in the gaps.