A storage device is provided. The storage device includes a memory controller and at least one nonvolatile memory device including memory blocks having a pipe-shaped bit cost scalable (PBiCS) structure. Each of the memory blocks penetrates word lines stacked on a substrate in the form of plates and includes a first pillar, a second pillar, and a back-gate. The second pillar includes a semiconductor layer, an insulating layer, and a charge storage layer. The back-gate includes a pillar connection portion to connect the first and second pillars to each other and is disposed between the substrate and the word lines. The memory controller includes an adjacent cell management unit configured to control the at least one nonvolatile memory device such that a program operation, an erase operation or a read operation is performed on memory cells adjacent to the back-gate, unlike the other memory cells.