1. A resource optimization method, comprising: estimating an amount of generated traffic that is anticipated to be generated, based on a number of subscribers to be processed by a virtual machine; selecting, when the estimated amount of generated traffic exceeds an optimum value predetermined as throughput of physical hardware on which the virtual machine operates, an optimum physical hardware that has a margin for processing the amount of generated traffic, and live-migrating the virtual machine to the selected physical hardware, comparing a result obtained by monitoring actual traffic with the amount of generated traffic estimated based on the number of subscribers; and performing, when there is caused a wide gap that is greater than or equal to a predetermined threshold between the result and the amount of generated traffic, a notification to a maintainer to prompt a review of settings on the amount of generated traffic estimated based on the number of subscribers.