A memory device may be provided which includes a memory cell array including a plurality of sub arrays each sub array having a plurality of memory cells connected to bit lines; an address buffer configured to receive a row address and a column address; and a column decoder configured to receive the column address from the address buffer and, for each of the sub arrays, to select a column selection line corresponding to the column address, from among a plurality of column selection lines, based on different offset values applied to the sub arrays, respectively. The selected column selection lines correspond to bit lines having different physical locations, respectively, according to the different offset values.