1. A non-transitory computer-readable recording medium having stored therein a patch scheduling program that causes a computer to execute a process comprising: managing a system including a plurality of software that control a plurality of virtual machines; aggregating virtual machines including a similar trend regarding a predetermined index thereof with a mutually-same virtual software; determining a time period during which the virtual machines are to be moved, based on the trends of the virtual machines aggregated with the mutually-same virtual software and based on moving time of the move of the virtual machines to a different virtual software included in the plurality of virtual software; and scheduling applying a patch to each of the plurality of virtual software at the determined time periods.