An electric power adjustment system includes a fuel cell connected to a load, and a multi-phase converter connected between the fuel cell and the load. The multi-phase converter is constituted of a plurality of phases and converts an output voltage from the fuel cell by a predetermined required voltage ratio. The electric power adjustment system includes a ripple current characteristic switching unit configured to switch a ripple current characteristic with respect to an input current to the multi-phase converter by changing at least one of a drive phase number and the voltage ratio of the multi-phase converter according to an operation state of the fuel cell and a required electric power of the load.