A power supply system includes a plurality of power supply apparatuses whose inputs and outputs are respectively connected in parallel with one another. The output of each of the plurality of power supply apparatuses is wired-OR connected to a synchronization pulse bus line in an open collector structure or an open drain structure. The plurality of power supply apparatuses each include a synchronization pulse generator generating a synchronization pulse for synchronization of a switching cycle, and a switching control circuit, connected to the synchronization pulse bus line, performing switching control of a switch device in synchronization with a signal of the synchronization pulse bus line. There is no distinction between a master power supply apparatus and a slave power supply apparatus in the plurality of power supply apparatuses. Further, generation of noise due to a transmission line for a synchronization signal is avoided.