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. <EOS>