An electronic component mounting system configured by joining together a plurality of electronic component mounting apparatuses (M2) to (M5*), each of which has a first mounting lane (L1) and a second mounting lane (L2), is configured so as to be able to carry out any one selected from a first operation mode of letting one operation performance mechanism carry out operation performance while taking as a target only a substrate of a substrate conveyance mechanism corresponding to the operation performance mechanism and a second operation mode in which one operation performance mechanism can carry out operation performance while taking as targets all of a plurality of substrates conveyed by a plurality of substrate conveyance mechanisms, and only the two electronic component mounting apparatuses (M5*) each of which is equipped with a tray feeder (30) is brought into the second operation mode.