A power supply comprising: a light emission module including a plurality of boards (B1,..., Bn); a power source supplying a Direct Current voltage to the light emission module; and a feedback control unit varying the DC voltage supplied from the power source according to the number of the boards (B1,..., Bn) of the light emission module, wherein the plurality of boards (B1,..., Bn) are electrically connected to each other and physically separated from each other, each of the boards (B1,..., Bn) comprises: a light emission unit (121,..., 12n); and a board resistor (R1,..., Rn), wherein the board resistor (R1,..., Rn) is a setting resistor for sensing whether the light emission units (121,..., 12n) of the boards (B1,..., Bn) are connected, the feedback control unit comprises a resistor connected to a reference voltage; a reference potential unit outputting a voltage value which is obtained through voltage division of the reference voltage by the resistor and the board resistors (R1,..., Rn); and a comparator controlling an output current of the power source, the voltage value is changed according to the number of the boards (B1,..., Bn) of the light emission module, the board resistors (R1,..., Rn) are electrically connected to each other, and the feedback control unit varies an input current of the light emission units according to the number of the boards (B1,..., Bn) of the light emission module, characterized in that the board resistors (R1,..., Rn) are disconnected from the light emission units (121,..., 12n), and by the comparator comparing the voltage value output of the reference potential unit and a value of an output terminal in each of the light emission units (121,..., 12n) to output a signal to the power source according to the comparison result. a light emission module including a plurality of boards (B1,..., Bn); a power source supplying a Direct Current voltage to the light emission module; and a feedback control unit varying the DC voltage supplied from the power source according to the number of the boards (B1,..., Bn) of the light emission module, wherein the plurality of boards (B1,..., Bn) are electrically connected to each other and physically separated from each other, each of the boards (B1,..., Bn) comprises: a light emission unit (121,..., 12n); and a board resistor (R1,..., Rn), a light emission unit (121,..., 12n); and a board resistor (R1,..., Rn), wherein the board resistor (R1,..., Rn) is a setting resistor for sensing whether the light emission units (121,..., 12n) of the boards (B1,..., Bn) are connected, the feedback control unit comprises a resistor connected to a reference voltage; a reference potential unit outputting a voltage value which is obtained through voltage division of the reference voltage by the resistor and the board resistors (R1,..., Rn); and a comparator controlling an output current of the power source, the voltage value is changed according to the number of the boards (B1,..., Bn) of the light emission module, the board resistors (R1,..., Rn) are electrically connected to each other, and the feedback control unit varies an input current of the light emission units according to the number of the boards (B1,..., Bn) of the light emission module, characterized in that the board resistors (R1,..., Rn) are disconnected from the light emission units (121,..., 12n), and by the comparator comparing the voltage value output of the reference potential unit and a value of an output terminal in each of the light emission units (121,..., 12n) to output a signal to the power source according to the comparison result.