A semiconductor device and a method of fabricating the same are disclosed. The semiconductor device includes: a memory cell structure formed over a semiconductor substrate; a channel portion formed in the semiconductor substrate; a through-hole formed to pass through the memory cell structure; a first channel region formed over sidewalls of the through-hole; and a second channel region formed at a center part of the through-hole, and spaced apart from the first channel region, wherein each of the first channel region and the second channel region is coupled to the channel portion.