A magneto-resistive random access memory (MRAM) including an MRAM cell array having an MRAM cell, and a control and voltage generation unit configured to generate a back bias voltage for the MRAM cell. The control and voltage generation unit including a command decoder configured to generate a decoding signal in response to a command output from a memory controller, and a voltage controller and generator configured to generate the back bias voltage with a magnitude based on the decoding signal and a reset signal output from the memory controller.