Provided is an IT system to minimize occurrence of a bottleneck on a network while effectively making use of the bandwidth of the network. A system management apparatus collects performance information from a network device, and calculates the average value, the peak hour, and the variance from the collected performance information. In response to a request for addition of a business system, the system management apparatus builds configuration patterns of a group of virtual servers configuring the business system and monitors traffic states of the paths on the network, identifies the part of the network where the traffic quality is most degraded, and determines the pattern that includes the path which has the smallest variance in the traffic based on traffic information on the part where the communication quality is degraded identified in each pattern as the requested system configuration of the business system.