A reactive power control device includes a limit value deriver configured to derive a limit value of reactive power, which is output by one or a plurality of power conversion devices determined for system stabilization and control of a system voltage, on the basis of a voltage of a point other than a voltage control target, and a command value adjuster configured to adjust a reactive power command value for the one or plurality of power conversion devices on the basis of the limit value derived by the limit value deriver.