There are a lot of e-commerce sites in the Internet today. In the flood of similar e-commerce sites, there is keen competition among them. To strengthen the competitiveness of e-commerce sites and to understand their customer carefully, customer data, clickstream data, transaction data and etc. are collected. The collected data is analyzed and the analysis result is used for site management and marketing. However, to adopt E-market state that is changing rapidly, each e-commerce site must grasp the trend of rival company and forecast future E-market place. To do that, first of all, commerce data across multiple e-commerce sites is needed. So, we propose Integrated E-Market Analysis System(IEMAS), a new system that collects transaction data across multiple e-commerce sites, analyzes the collected data and provides analysis results to e-commerce site. We design and implement the system, and show some possible opportunity which could be obtained using our system by case study. By using Integrated E-market Analysis System(IEMAS), e-commerce sites can acquire information about not only their own business but also E-market trend and business interrelationship across multiple e-commerce sites.