When information on a device such as a server, storage, and an FC switch constituting a SNA system is input, these devices are displayed and arranged properly on a screen (S1, S2). When information on a physical path is input by a designer by using this display screen, a virtual SAN system in which the devices are connected by a fiber channel is displayed on the screen (S3). Furthermore, when information on an access path is input by the designer by using the construction image, the access path is additionally displayed on the construction image of the virtual SAN system (S5). Since the construction image of the virtual SAN system is displayed on the screen, the designer can easily create a design drawing while visually checking the SAN system. This can reduce the work load and time required for construction of the SAN system.