This research is to suggest the factor which is effecting on the information system audit fidelity in the perspective of audit procurer, to develop the measure to evaluate it, to investigate the audit performance and project performance for comparison the audit fidelity between the audit teams. As the analysis results, we found that the audit service factors can be divided to the expert knowledge of auditor and the project attributes itself. It means these factors are the major measures for the audit fidelity. In this research, the hypothesis of this study model is verified throughout the factor and corelation analysis, and the structured equation model is applied. Analysis results show that all relations between the factors are significant statistically. The audit service factors has an effect on audit fidelity. Also the information system audit fidelity can be affect on the project performance, audit performance and customer satisfaction. So, in conclusion, we need to judge closely the audit service factors affecting the audit fidelity for the enhancement of the project performance, audit performance and customer satisfaction.