A three-dimensional (3D) semiconductor memory device comprises memory cell strings each comprising at least one selection transistor and at least one memory cell, a first pass transistor group sharing a first well region and comprising a first selection line pass transistor connected to the selection transistor and a first world line pass transistor connected to the memory cell, a second pass transistor group sharing a second well region and comprising a second selection line pass transistor connected to the selection transistor, and a controller that controls the first pass transistor group and the second pass transistor group. The controller applies selected voltages to the first and second well regions during read operation.