A dust collector (10) has a main body (12), the interior of which is divided by a tubular partition wall (26) into a central filtration chamber (30) and an outwardly-located annular cyclone chamber (32). At the upper part of the cyclone chamber (32), there is provided a water supply pipe (36) having radially directed nozzles (38) adapted to form a water film flowing down along the inner circumferential surface of the main body (12) and the-outer circumferential surface of the partition wall (26), respectively. Air to be treated is drawn under suction through an air intake (34) into the cyclone chamber (32) and swirling air is brought into contact with the water film whereby dust and particles are preliminarily collected while retaining an explosion-proof function. The cyclone chamber (32) and the filtration chamber (30) are communicated with each other at the lower portion thereof to permit the thus pretreated air to be drawn into the filtration chamber (30). Filters (44) are arranged in the filtration chamber (30) so as to further collect dust and particles by filtration. A small and compact dust collector capable of effectively collecting fine particles and small in air-flow resistance and pressure drop and having an excellent explosion-proof capability can be provided.