A demand-response system includes first and second aggregators and a power aggregator. The first aggregator performs demand-response-related control of a first heating device group including a heat pump device, and the second aggregator performs demand-response related control of a second heating device group. The power aggregator sends a second power adjustment request to the first and second aggregators using a command being common to the first and second aggregators. In accordance with the second power adjustment request, the first aggregator performs demand-response-related control of the first heating device group using a first dedicated command, and the second aggregator performs demand-response-related control of the second heating device group using a second dedicated command that is different from the first dedicated command.