A demand response method comprising: recognizing a demand response level established in each household appliance (30_1, 30_2, 30_3, 30_4, 30_n) so as to limit a function of each household appliance (30_1, 30_2, 3Q_3, 30_4, 30_n); establishing priority information of each household appliance (30_1, 30_2, 30_3, 30_4, 30_n); determining, if the demand response level established in the household appliance (30_1, 30_2, 30_3, 30_4, 30_n) needs to be changed, a household appliance having a demand response level to be changed according to the priority information and the demand response level of each household appliance (30_1, 30_2, 30_3, 30_4, 30_n); determining a quality status of each recognized household appliance (30_1, 30_2, 30_3, 30_4, 30_n) by receiving a quality factor indicating performance of the household appliance (30_1, 30_2, 30_3, 30_4, 30_n), and determining a quality status of each household appliance (30_1, 30_2, 30_3, 30_4, 30_n) in response to the received quality factor, and establishing the priority information of each household appliance (30_1, 30_2, 30_3, 30_4, 30_n) in response to quality status variation, characterized by determining a changeable demand response level range of each household appliance (30_1, 30_2, 30_3, 30_4, 30_n) in response to the determined quality status, wherein the determining of the demand response level range comprises reducing the changeable demand response level range in proportion to lowering of the determined quality status; and changing, if the demand response level established in the household appliance (30_1, 30_2, 30_3, 30_4, 30_n) needs to be changed, a demand response level established in the determined household appliance (30_1, 30_2, 30_3, 30_4, 30_n) on the basis of the determined demand response level range. recognizing a demand response level established in each household appliance (30_1, 30_2, 30_3, 30_4, 30_n) so as to limit a function of each household appliance (30_1, 30_2, 3Q_3, 30_4, 30_n); establishing priority information of each household appliance (30_1, 30_2, 30_3, 30_4, 30_n); determining, if the demand response level established in the household appliance (30_1, 30_2, 30_3, 30_4, 30_n) needs to be changed, a household appliance having a demand response level to be changed according to the priority information and the demand response level of each household appliance (30_1, 30_2, 30_3, 30_4, 30_n); determining a quality status of each recognized household appliance (30_1, 30_2, 30_3, 30_4, 30_n) by receiving a quality factor indicating performance of the household appliance (30_1, 30_2, 30_3, 30_4, 30_n), and determining a quality status of each household appliance (30_1, 30_2, 30_3, 30_4, 30_n) in response to the received quality factor, and establishing the priority information of each household appliance (30_1, 30_2, 30_3, 30_4, 30_n) in response to quality status variation, characterized by determining a changeable demand response level range of each household appliance (30_1, 30_2, 30_3, 30_4, 30_n) in response to the determined quality status, wherein the determining of the demand response level range comprises reducing the changeable demand response level range in proportion to lowering of the determined quality status; and changing, if the demand response level established in the household appliance (30_1, 30_2, 30_3, 30_4, 30_n) needs to be changed, a demand response level established in the determined household appliance (30_1, 30_2, 30_3, 30_4, 30_n) on the basis of the determined demand response level range.