A damper switch for opening/closing a plurality of blades of a damper, the damper switch comprising: a rotating part mounted on a damper shaft of the damper and rotated together with the damper shaft; a driving part configured to provide a power for rotating the rotating part; and a controller configured to measure a load applied to the driving part when the blades are closed, and interrupt an electric power supplied to the driving part when the measured load is not less than a predetermined value, wherein the rotating part comprises: a rotary shaft having an insertion hole into which the damper shaft is inserted; and a rotating plate coupled to a circumference of the rotary shaft; further comprising a sensor unit having a pair of optical sensors located on opposite sides with the rotary shaft interposed therebetween, wherein through-holes are formed in the rotary shaft in a direction in which the through-holes cross the insertion hole, wherein the sensor unit generates an electric signal when the through-holes are arranged in parallel to the pair of optical sensors, and wherein the controller interrupts an electric power supplied to the driving part when receiving the electric signal from the sensor unit, characterized in that the damper switch is configured such that when the damper shaft is inserted into the rotary shaft, and the through-holes are thus blocked, even when the through-holes are arranged in parallel to the pair of optical sensors, the electric signal is not generated. a rotating part mounted on a damper shaft of the damper and rotated together with the damper shaft; a driving part configured to provide a power for rotating the rotating part; and a controller configured to measure a load applied to the driving part when the blades are closed, and interrupt an electric power supplied to the driving part when the measured load is not less than a predetermined value, wherein the rotating part comprises: a rotary shaft having an insertion hole into which the damper shaft is inserted; and a rotating plate coupled to a circumference of the rotary shaft; further comprising a sensor unit having a pair of optical sensors located on opposite sides with the rotary shaft interposed therebetween, wherein through-holes are formed in the rotary shaft in a direction in which the through-holes cross the insertion hole, wherein the sensor unit generates an electric signal when the through-holes are arranged in parallel to the pair of optical sensors, and wherein the controller interrupts an electric power supplied to the driving part when receiving the electric signal from the sensor unit, characterized in that the damper switch is configured such that when the damper shaft is inserted into the rotary shaft, and the through-holes are thus blocked, even when the through-holes are arranged in parallel to the pair of optical sensors, the electric signal is not generated. a rotary shaft having an insertion hole into which the damper shaft is inserted; and a rotating plate coupled to a circumference of the rotary shaft; further comprising a sensor unit having a pair of optical sensors located on opposite sides with the rotary shaft interposed therebetween, wherein through-holes are formed in the rotary shaft in a direction in which the through-holes cross the insertion hole, wherein the sensor unit generates an electric signal when the through-holes are arranged in parallel to the pair of optical sensors, and wherein the controller interrupts an electric power supplied to the driving part when receiving the electric signal from the sensor unit, characterized in that the damper switch is configured such that when the damper shaft is inserted into the rotary shaft, and the through-holes are thus blocked, even when the through-holes are arranged in parallel to the pair of optical sensors, the electric signal is not generated.