An apparatus for driving a wearable robot includes a wire having one end connected to an arm of the wearable robot, a tension detector that is provided between the one end and the other end of the wire and detects tension of the wire, a driver that is connected to the other end of the wire and winds or unwinds the wire, and a controller that controls the driver to be operated to wind or unwind the wire when the arm rotates to change the tension of the wire so that the wire maintains a preset reference tension.