A demand response system and method. The demand response system includes a power rate reception unit for receiving information about charge rates for a unit of power from an external power trading server. An amount-of-power used reception unit receives information about amounts of power used by a customer from a gateway, a first data generation unit which generates first data including information about charge rates for a unit of power for respective time spans, a second data generation unit which generates second data including information about amounts of power used by the customer for the respective time spans, and a third data generation unit which generates third data including information about index power charges for the customer for the respective time spans.