The utilization efficiency of physical resources is increased by allocating an occupied physical CPU core to a virtual CPU core in a virtual machine in a working system and allocating a shared physical CPU core to a virtual CPU core of a virtual machine in a standby system in a state in which the systems are active. A dedicated activation core, a shared core, or an occupied core is allocated when the respective virtual machines are activated, the resource allocation is changed after the respective virtual machines are activated, and the shared core and the occupied core are appropriately assigned to the working system and the standby system. In a case in which a failure occurs in the virtual machine of the working system, allocation of the shared core allocated to the other virtual machine in the pair is changed into an occupied state to avoid degradation of performance.