Purpose - The purpose of this study was to structurally verify how the competency of consulting company affects the business performance of consulting client firms through consulting achievement and consulting utilization. It aims to provide information for successful consulting and suggest strategic measures to improve consulting performance. Research design, data, and methodology - This study examines the structural relationship between competency of consulting company, consulting performance, and performance of consulting client firms. In this model, competency of consulting company consists of three sub-dimensions such as reputation, ability to perform business, and expertise. For these purposes, research model and hypotheses were developed. This survey was conduct ed for employees of companies that have experienced consulting in the past year. A total of 195 were used for this study. The data were analyzed using frequency analysis, confirmatory factor analysis, correlation analysis, and SEM with SPSS 18.0 and Amos 18.0 statistical program. Result - The results of this study are as follows. First, reputation, ability to perform business and expertise, which are sub-dimensions of consulting competence, was found to have positive effect on consulting achievements and also found to have a positive effect on utilization. Second, consulting performance was found to have positive effects on business performance of consulting client firms. It means that the management's willingness to utilize consulting results and the achievements of consulting performance have a positive effect on the company's management performance. Conclusions - Consulting firms need to perform customer-oriented consulting by accurately recognizing what management consulting is required by the client firms. The academic significance of this study was that the research was conducted through structural empirical analysis, not only from the relationship of competency of consulting company to consulting performance, but also to the relationship of business performance of client firms. In addition, the practical implication of this study is that clients can actively utilize the results of consulting to lead business performance.