The present invention discloses a current balancing device and method capable of balancing an output current and an input current of a current loop. Said device comprises: a transmission circuit for outputting an output current and receiving an input current; at least one adjustable resistor set in the current loop for providing resistance according to at least one adjustment signal; and a current balancing circuit, coupled to the transmission circuit and the adjustable resistor, for determining whether the difference between the output and input currents satisfies a predetermined requirement in light of a predetermined duration and thereby generating the adjustment signal, wherein if the difference between the output and input currents fails to satisfy the predetermined requirement, the current balancing circuit will adjust the resistance of the adjustable resistor through the adjustment signal, so as to reduce the difference between the output and input currents.