A component mounting system that includes at least one 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, wherein a job comprises information, namely which type of which component will be mounted on board, in what order in each component mounter, how many boards mounted in this manner will be produced, and arrangement information which indicates the arrangement of component supply units in the supply area of each component mounter for the mounting process, the system comprising: a unit exchange device configured to be able to automatically exchange the component supply unit with a predetermined number as an upper limit, which is two or more and which is the upper limit number of component supply units, that the unit exchange device can collectively exchange in one exchange operation, for each exchange operation between the unit exchange device and the supply area and between the unit exchange device and a preparation area different from the supply area; and a control device configured to perform, a preparatory arrangement control for controlling the unit exchange device such that the component supply units required for the next job are arranged in preparation area and configured to perform grouping of component supply units in groups (S1-S4) having a number of supply units corresponding to the predetermined number with allowing a number less than the predetermined number for the last group, and controlling the unit exchange device so as to make an arrangement of the component supply units in each group match an arrangement order in the supply area as defined in the job and to collectively arrange the component supply units in the preparation area for each group, and a supply arrangement control configured to output an instruction to the unit exchange device to collectively transfer a group (S1-S4) of component supply units having a number of component supply units corresponding to the predetermined number from preparation area to a place in supply area so as to automatically exchange the component supply units arranged in the preparation area by the preparatory arrangement control and the component supply units already arranged in the supply area before switching the job, and so that the component supply units are arranged at a place that matches the arrangement order in the supply area as defined in the job information. a unit exchange device configured to be able to automatically exchange the component supply unit with a predetermined number as an upper limit, which is two or more and which is the upper limit number of component supply units, that the unit exchange device can collectively exchange in one exchange operation, for each exchange operation between the unit exchange device and the supply area and between the unit exchange device and a preparation area different from the supply area; and a control device configured to perform, a preparatory arrangement control for controlling the unit exchange device such that the component supply units required for the next job are arranged in preparation area and configured to perform grouping of component supply units in groups (S1-S4) having a number of supply units corresponding to the predetermined number with allowing a number less than the predetermined number for the last group, and controlling the unit exchange device so as to make an arrangement of the component supply units in each group match an arrangement order in the supply area as defined in the job and to collectively arrange the component supply units in the preparation area for each group, and a supply arrangement control configured to output an instruction to the unit exchange device to collectively transfer a group (S1-S4) of component supply units having a number of component supply units corresponding to the predetermined number from preparation area to a place in supply area so as to automatically exchange the component supply units arranged in the preparation area by the preparatory arrangement control and the component supply units already arranged in the supply area before switching the job, and so that the component supply units are arranged at a place that matches the arrangement order in the supply area as defined in the job information.