A power supply system is disclosed. The system includes a power supply unit which supplies power to a processing unit, an arrival time calculating portion which calculates arrival time taken for a lot to arrive at the processing unit from a present position based on the state of the lot, a comparing portion which compares the arrival time with start-up time of the processing unit, and a supply control portion which controls the power supply unit. The supply control portion causes operation power to be supplied to the processing unit when the arrival time is equal to or shorter than the start-up time and causes saving power which is smaller than the operation power to be supplied to the processing unit when the arrival time is longer than the start-up time.