Disclosed is a dust collector (30) that is disposed in an air passageway (15) to which water droplets (21a) are supplied, and that includes a dust collecting electrode portion (31b) which electrically attracts dust charged in the air. The dust collecting electrode portion (31b) is made of a plate-like member having a mesh-like structure with a plurality of pores, thereby reducing an interfacial tension between the water droplets (21a) adhering on the surface of the dust collecting electrode portion (31b) and the dust collecting electrode portion (31b). Thus, water droplets are prevented from increasing in size on the surface of a dust collecting electrode, and a decrease in the dust collection capability due to adhesion of dust or the like is reduced.