To improve operability and maintainability of a resource allocation processing system by allocating resources other than the resource information stored in extended boards when the same resource is needed by plural extended boards.

If the same resource is needed by plural extended boards, a forced resource allocation processing part 1-2 of a computer main body allocates the resources other than the resource information stored in the extended boards. If the part 1-2 allocates a virtual resource that does not actually exist, a resource operation conversion processing part 1-3 relates the virtual resource with an existing resource to secure the use of the extended boards. If it is impossible to obtain the resources which are necessary for the vtilization of the extended boards by the resources that are useable by the computer main body alone, the part 1-2 allocates a virtual resource and notifies the part 1-3 of this allocation. The part 1-3 converts the operation to be applied to the virtual resource into the operation to be applied to the real resource.