A system for controlling an electric device operation comprising: a plurality of loads (23a-23n) managed by a consumer associated with a power system; a plurality of control devices (24a-24n) for controlling an operation of the loads (23a-23n); characterized by: an operation time calculation unit configured to calculate a start time of an operation of increasing or decreasing power received from the plurality of loads (23a-23n) based on a control command for requesting an increase or decrease of power received from the power system such that the start time is different for each of the loads (23a-23n); a power rate storage unit for storing power rates related to the loads (23a-23n); and an operation time storage unit for storing an operation schedule time of the loads (23a-23), the operation time calculation unit: calculates an operation time of each load (23a-23n) and a temporary response time (Ta-Te) of the loads (23a-23n) based on the power rate stored in the power rate storage unit; calculates a correction time (t) to equalize the sums of power rates before and after the power rates are changed while maintaining the time interval of the temporary response time (Ta-Te), based on the temporary response time (Ta-Te) of the loads (23a-23n), the time (tc) at which the power rate is changed, a power rate (Pp) before the time (tc) at which the power rate is changed, and a power rate (Pa) after the time (tc) at which the power rate is changed; and obtains a formal response time of the loads (23a-23n) by adding the correction time (t) to the temporary response time (Ta-Te). a plurality of loads (23a-23n) managed by a consumer associated with a power system; a plurality of control devices (24a-24n) for controlling an operation of the loads (23a-23n); characterized by: an operation time calculation unit configured to calculate a start time of an operation of increasing or decreasing power received from the plurality of loads (23a-23n) based on a control command for requesting an increase or decrease of power received from the power system such that the start time is different for each of the loads (23a-23n); a power rate storage unit for storing power rates related to the loads (23a-23n); and an operation time storage unit for storing an operation schedule time of the loads (23a-23), the operation time calculation unit: calculates an operation time of each load (23a-23n) and a temporary response time (Ta-Te) of the loads (23a-23n) based on the power rate stored in the power rate storage unit; calculates a correction time (t) to equalize the sums of power rates before and after the power rates are changed while maintaining the time interval of the temporary response time (Ta-Te), based on the temporary response time (Ta-Te) of the loads (23a-23n), the time (tc) at which the power rate is changed, a power rate (Pp) before the time (tc) at which the power rate is changed, and a power rate (Pa) after the time (tc) at which the power rate is changed; and obtains a formal response time of the loads (23a-23n) by adding the correction time (t) to the temporary response time (Ta-Te). an operation time calculation unit configured to calculate a start time of an operation of increasing or decreasing power received from the plurality of loads (23a-23n) based on a control command for requesting an increase or decrease of power received from the power system such that the start time is different for each of the loads (23a-23n); a power rate storage unit for storing power rates related to the loads (23a-23n); and an operation time storage unit for storing an operation schedule time of the loads (23a-23), the operation time calculation unit: calculates an operation time of each load (23a-23n) and a temporary response time (Ta-Te) of the loads (23a-23n) based on the power rate stored in the power rate storage unit; calculates a correction time (t) to equalize the sums of power rates before and after the power rates are changed while maintaining the time interval of the temporary response time (Ta-Te), based on the temporary response time (Ta-Te) of the loads (23a-23n), the time (tc) at which the power rate is changed, a power rate (Pp) before the time (tc) at which the power rate is changed, and a power rate (Pa) after the time (tc) at which the power rate is changed; and obtains a formal response time of the loads (23a-23n) by adding the correction time (t) to the temporary response time (Ta-Te). calculates an operation time of each load (23a-23n) and a temporary response time (Ta-Te) of the loads (23a-23n) based on the power rate stored in the power rate storage unit; calculates a correction time (t) to equalize the sums of power rates before and after the power rates are changed while maintaining the time interval of the temporary response time (Ta-Te), based on the temporary response time (Ta-Te) of the loads (23a-23n), the time (tc) at which the power rate is changed, a power rate (Pp) before the time (tc) at which the power rate is changed, and a power rate (Pa) after the time (tc) at which the power rate is changed; and obtains a formal response time of the loads (23a-23n) by adding the correction time (t) to the temporary response time (Ta-Te).