A dust collector includes a shell, an exit tube, an inner tube, a suction device, a first dust container, a bypass tube and a first dust bag. The shell defines a first receiving room therein. The exit tube defines an exit passage therein. The inner tube defines a connection passage which has a first opening and a second opening. The first opening communicates the first receiving room, and the second opening communicates the exit passage. The suction device provides the exit passage with a negative pressure. The first dust container defines a second receiving room therein. A mesh is disposed on a bottom surface of the first dust container to divide the second receiving room into a first chamber and a second chamber. The bypass tube defines a bypass passage therein, and it communicates the connection passage with the second chamber. The first dust bag is disposed in the first chamber.