This invention is a new structure of blackboard eraser with cordless vacuum functionality. The main components in the design include a chalk eraser, chalk dust collector and vacuum fan. A brusher mounted in the edge of inlet hole of chalk dust collector removes the chalk dust from the surface of eraser belt shape fabric and then the chalk dust is vacuumed into the collector chamber by vacuum fan. The roller shafts are inserted to the eraser bracket side holes and then go to the center of cylinder rollers.The eraser belt shape fabric covers to the external of the four rollers and eraser bracket. The eraser belt fabric will be conveyed back and forth by the friction with rollers and erase the chalk dust from the blackboard. One filter bag installed in the collect chamber filters the chalk power from the inlet air of the vacuum fan. The vacuum function driven by fan and electric motor can transport the chalk power to the external surface of filter bag and no leaking to the outside and that harms the health for anyone nearby. The built-in rechargeable battery for the fan motor allows the eraser to be used cordlessly.