Provided is an integrated circuit device including a plurality of word lines overlapping each other, in a vertical direction, on a substrate, a plurality of channel structures extending in the vertical direction through the plurality of word lines on an area of the substrate, a plurality of bit line contact pads on the plurality of channel structures, and a plurality of bit lines, wherein the plurality of bit lines include a plurality of first bit lines extending parallel to each other at a first pitch in a center region of the area, and a plurality of second bit lines extending at a second pitch in an edge region of the area, the second pitch being different from the first pitch.