A component mounting system comprising: a component mounting machine group made up by aligning multiple component mounting machines along a conveyance direction of a mounting target object (S), the component mounting machines each including multiple component supply devices (30; 301, 302) that are set detachably and configured to mount a component supplied by the component supply devices (30; 301, 302) onto the mounting target object (S); a storage container provided at an upstream side or a downstream side of the component mounting machine group and having a storage area configured to support detachably some of the multiple component supply devices (30; 301, 302) that are arranged in an aligned fashion; a loader configured to move along the conveyance direction to automatically detach and/or attach the component supply devices (30; 301, 302) from and/or to the component mounting machines and the storage container ; and a control section the component mounting system is characterized in that the control section is configured to predict a number of the component supply devices (30 301) for collection to set a the- boundary based on the number of the component supply devices (30; 301) for collection so predicted, wherein the storage area is divided by the boundary into a collection area (a1) configured to detachably support the component supply device (30; 301) for collection that is not used for production and a supply area (a2) configured to detachably support the component supply device (30; 302) for supply that is used for production, and wherein in setting the boundary , the control section causes a boundary position indicator provided in the storage area to indicate the boundary . a component mounting machine group made up by aligning multiple component mounting machines along a conveyance direction of a mounting target object (S), the component mounting machines each including multiple component supply devices (30; 301, 302) that are set detachably and configured to mount a component supplied by the component supply devices (30; 301, 302) onto the mounting target object (S); a storage container provided at an upstream side or a downstream side of the component mounting machine group and having a storage area configured to support detachably some of the multiple component supply devices (30; 301, 302) that are arranged in an aligned fashion; a loader configured to move along the conveyance direction to automatically detach and/or attach the component supply devices (30; 301, 302) from and/or to the component mounting machines and the storage container ; and a control section the component mounting system is characterized in that the control section is configured to predict a number of the component supply devices (30 301) for collection to set a the- boundary based on the number of the component supply devices (30; 301) for collection so predicted, wherein the storage area is divided by the boundary into a collection area (a1) configured to detachably support the component supply device (30; 301) for collection that is not used for production and a supply area (a2) configured to detachably support the component supply device (30; 302) for supply that is used for production, and wherein in setting the boundary , the control section causes a boundary position indicator provided in the storage area to indicate the boundary . <EOS>