A memory device is provided. The memory device includes at least one memory bank, at least one first address decoder set, and at least one second address decoder set. Each of the at least one memory bank includes a plurality of memory cell arrays. Each of the at least one second address decoder set includes a plurality of second address decoders. The at least one second address decoder set receives a plurality of column select lines to perform an access operation on memory cells of the memory cell arrays. The column select lines are divided into a plurality of column select line groups, and each of the column select line groups is assigned to the second address decoder corresponding thereto, wherein the number of the column select lines allocated to each of the column select line groups is less than a total number of the column select lines.