A memory device may include an insulating structure including a first surface and a protrusion portion protruding from the first surface in a first direction, a recording material layer on the insulating structure and extending along a protruding surface of the protrusion portion to cover the protrusion portion and extending onto the first surface of the insulating structure, a channel layer on the recording material layer and extending along a surface of the recording material layer, a gate insulating layer on the channel layer; and a gate electrode formed on the gate insulating layer at a location facing a second surface of the insulating structure. The second surface of the insulating structure may be a protruding upper surface of the protrusion portion.