A computer, on which operating systems run, the computer comprising a virtualization function module configured to manage virtual computers. A operating system is configured to run on each of the virtual computers. The virtualization function module includes an interrupt controller. The interrupt controller is configured to hold vector information for managing host-side interrupt vectors, and interrupt vector allocation information for managing allocation of the host-side interrupt vectors to the guest-side interrupt vectors that are set by the operating systems. The virtualization function module is configured to analyze a state of allocation of the host-side interrupt vectors to the guest-side interrupt vectors, and change the allocation of the host-side interrupt vectors to the guest-side interrupt vectors based on a result of the analysis.