In a case where a variation in reflection resistance among fiber lasers occurs, a reflection resistance of a fiber laser system as a whole is restored by reducing the variation while maintaining an output power of the fiber laser system as a whole. The fiber laser system includes a control section (C) configured to increase a proportion of a backward excitation power (PBi) in a fiber laser (FLi) so that fiber lasers (FL1 through FLn) less vary in reflection resistance.