Disclosed is a processing apparatus. The processing apparatus includes: a load port in which a conveyance container accommodating a plurality of semiconductor wafers is placed; a dummy wafer storage area in which a conveyance container accommodating a plurality of dummy wafers is placed; a normal-pressure conveyance room in which a first conveyance arm is installed; an equipment that processes the plurality of semiconductor wafers in a state where the semiconductor wafers and the dummy wafers which are conveyed are placed in slots, respectively; and a controller that controls each component of the processing apparatus. The controller classifies the dummy wafers accommodated in the conveyance container into a plurality of groups, and controls the first conveyance arm to preferentially convey the dummy wafers within one of the classified groups to the equipment and, in replacing the dummy wafers, to perform replacement of the dummy wafers group to group as classified.