An EMS includes a control unit that controls a power generation facility and a power adjustment unit that adjusts an amount of supply of supply power. The control unit includes: a reverse power flow suppression process determination unit; a priority decision unit that decides a priority for adjusting an amount of power generated for the two power generation devices of the power generation facility on the basis of a predicted degree of fluctuation in load power; and a device control unit that controls the power generation facility such that the amount of power generated is adjusted in descending order of the priority decided by the priority decision unit when the reverse power flow suppression process determination unit determines to reduce the amount of power generated by the power generation facility.