A virtual machine management apparatus connected to a plurality of server devices via a network generates a new virtual machine on a server device in accordance with a request from a management terminal. At that time, for one or more server devices to which a new virtual machine can be allocated, the virtual machine management apparatus refers to an allocation rule table for storing a score for each of combinations of types of virtual machines. The score indicates appropriateness of a condition that each combination of types of virtual machines is to be allocated to the same server device. Thus, the virtual machine management apparatus computes an index value indicative of appropriateness of a condition that the new virtual machine is to be allocated to the server device. Then the virtual machine management apparatus determines an allocation target for the new virtual machine with reference to the computed index value.