In this paper, the survey results of the interruption on domestic residential customer with primary focus on the cost are presented. General method utilized in quantifying the benefit of reliability on power system is to estimate the Customer Interruption Cost(CIC) associated with the electric service interruption. According to change the circumstance of electricity market by the deregulation and the introduction of new technology, reliable and accurate CIC is required for estimate the applied plan and technology under the circumstance. This paper presents the residential customer interruption cost is estimated by the survey conducted by KEPCO in 2009. To collect the customer interruption data for calculation of CIC, the survey is conducted. The survey targeting residential customer around the branch-offices under twelve regional headquarters of KEPCO was carried out.