When a wafer (W101) to be returned from a second cluster (12) to a first cluster (10) is delivered to a pass area (PA), a vacuum transfer robot (RB1) in the first cluster (10) performs serial transportation in the first cluster (10) preferentially while keeping the wafer (W101) at the pass area (PA). Subsequently, the vacuum transfer robot (RB1), holding a wafer (W104) to be sent from the first cluster (10) to the second cluster (12) by one arm thereof, receives the wafer (W101) existing in the pass area (PA) by the other arm thereof and delivers the wafer (W104) to the pass area (PA) instead, through pick and place operation. According to the procedure, throughput of continuous processing employing a plurality of process modules of two clusters (multi-chamber apparatuses) (10, 12) is improves as much as possible.