A generator system, including first and second generators each having an inverter circuit outputting AC, a connection circuit connecting the generators through a power line, a master-slave determining unit determining one of the generators as a master generator, and to determine other of the generators as a slave generator, a data acquiring unit acquiring an output data of the master generator, and a synchronization controlling unit controlling switching operation of the inverter circuit of the slave generator based on the output data of the master generator to synchronize an output data of the slave generator with the output data of the master generator, wherein the master-slave determining unit determines one of the generators that starts earlier as the master generator, and when the generators start simultaneously, to determine one of the generators as the master generator in accordance with a predefined rule.