A power supply includes a virtual machine state acquisition unit and a virtual machine management unit. The virtual machine state acquisition unit is configured to: send each of the virtual host computers in virtual host list data a request to acquire information on a virtual machine run in emulation by the virtual host computer; acquire, from each of the virtual host computers, the information on the virtual machine run in emulation by the virtual host computer; and create virtual machine management data in which an identifier of the virtual host computer, an identifier of the virtual machine thereof, and the acquired information on the virtual machine are associated with each other. The virtual machine management unit is configured to read the virtual machine management data and input a command related to a virtual power source of the virtual machine.