A method of controlling a virtual router includes: starting first and second virtual routers where a same address is set, on first and second networks; constructing, with respect to a plurality of virtual machines arranged in plural networks, a first virtual network that establishes coupling between first one or more virtual machines and coupling between the first one or more virtual machines and the first virtual router, and establishes coupling between second one or more virtual machines and coupling between the second one or more virtual machines and the second virtual router, the first one or more virtual machines being arranged on the first network, the second one or more virtual machines being arranged on the second network; constructing a second virtual network that establishes coupling between the first virtual router and the second virtual router; and creating and setting routing tables corresponding to the first and second virtual routers.