A memory device includes a first memory cell array including memory cells of a single-ended bitline structure, a second memory cell array including memory cells of a single-ended bitline structure, a reference voltage generator configured to output a bitline voltage of a selected one of the first and second memory cell arrays as a sensing voltage according to an array select signal and output a bitline voltage of an unselected memory cell array as a reference voltage, and a differential sense amplifier configured to amplify and output a difference between the sensing voltage and the reference voltage. Logic states of the sensing voltage and the reference voltage are complementary to each other.