While many services appear, it are performed in the various researches about a service. Among them, as to the basic reason for measuring the service level, in order to find out the strategy improving service quality. But the method for measuring quality of services up to date was unable to make it enough the role. This research tried to propose the approach systematically analyzing the human errors in order to improve service quality about the call center which utilizes the information technology. In fact, the human errors was found in the customer contact point in which the actual service is delivered. An interaction between the element for comprising call service was classified into 3 while defining the human error as 3 group. Moreover, the process where a service is delivered was classified according to 5 step and the generated error was measured in each step. The implication of this research looks at the service failure and dissatisfaction as the occurrence of the human errors and illustrates the service quality improvement as a correction or a reduction. This approach is used that service is materially easily understood and is formulated with the quality improvement strategy.