A memory device including a memory cell array including a first sub memory cell array including a first memory cell and a second sub memory cell array including a second memory cell, a merged write driver including a first write circuit receiving n-bit data (n being a natural number ≥2) through a write input/output line, outputting a first write voltage to a merged node in response to a first data bit of the n-bit data, and outputting a second write voltage to the merged node in response to a second data bit of the n-bit data, and a column decoder including a first column multiplexer applying a first voltage of the merged node corresponding to the first data bit to the first memory cell and a second column multiplexer applying a second voltage of the merged node corresponding to the second data bit to the second memory cell.