A component mounting system that includes a component mounter in which multiple component supply units are detachably arranged in a supply area and mounts components on a board based on a job. The system performs a preparatory arrangement control for dividing the component supply units required for the job into multiple, and controlling the unit exchange device to make an arrangement of the component supply units in each group match an arrangement order in the supply area, and a supply arrangement control for controlling the unit exchange device to automatically exchange the component supply units, and to arrange the component supply units required for the job after switching in the supply area.