A virtual resource automatic selection system includes a setting unit that sets, for a plurality of pieces of training data composed of two or more parameters, a classification boundary between virtual resource clusters that are ranked in accordance with a capacity of a virtual resource in terms of a relationship between the two or more parameters. When a construction request for a new virtual network is received, a receiving unit receives information composed of the parameters. A determining unit determines to which of the virtual resource clusters the parameters belong. An allocating unit allocates a capacity of a virtual resource to the virtual network. An acquiring unit acquires network performance information from the virtual network. A second determining unit determines whether the network performance information satisfies a desired quality of service. The setting unit updates the classification boundary in accordance with a determination result of the second determining unit.