A building-facility information storage stores data sizes of process data to be collected from building-side communicating devices. A schedule generating unit generates a collection schedule of the process data from the building-side communicating devices so that, in a collection period including a plurality of unit periods continuous in terms of time, a first communication load representing a total data volume received from the building-side communicating devices per unit period and second communication loads each representing a data volume transmitted from each of the building-side communicating devices per unit period are balanced among the unit periods. A network communicating unit collects the process data from the building-side communicating devices in accordance with the collection schedule.