A dust collector (1) is provided with a tank section (10) and a head section (20). The tank section (10) has a dust collection chamber (13) for containing dust. The head section (20) has a motor (23) and a dust collection fan (25). The dust collection chamber (13) has a cylindrical filter device (12) which, when air sucked in from the suction opening (11) flows through the filter device (12), separates dust from the air. A passage member (50) forms an air passage by which the outside air and a filter interior space (14) inside the filter device (12) are connected without having the filter device (12) therebetween. A cover body (60) closes the passage member (50) in an openable manner. The passage member (50) has first opening sections (53) facing the filter interior space (14) and located at different positions in the circumferential direction of the filter device (12).