Abstract: A dust collector separates dust from the gas including the dust such as smoke discharged from a coffee roasting machine. The dust collector uses a water spray. The dust collector can prevent blockage of nozzles of a upper water supply line and a side water supply line by arranging the upper nozzle and the side nozzle, which spray water, to be faced to each other within the body of the dust collector. Water flows along the side within the inlet which is slant downward, which allows the gas to flow into the body of the dust collector, and a separate assistant water supply line is connected to the inlet.