First brush bristles of an alignment stage cleaning mechanism are pressed on a wafer suction stage of the alignment stage before a semiconductor wafer is transported onto the alignment stage, in which state the wafer suction stage rotates to thereby remove dust attached to the wafer suction stage. Moreover, second brush bristles of a wafer chuck table cleaning mechanism are moved on and along a surface facing downward of a wafer chuck table to thereby remove dust attached to the surface facing downward of the wafer chuck table.