The storage part receives an I/O request including the ID of software, information regarding a storage area to and from which the software performs input and output, and a token. The storage part checks the I/O request against the software ID, the information regarding the storage area, and the token received from an I/O control part so as to determine whether access to the storage part is allowed. Upon determination that the access to the storage part is allowed, the storage part processes the I/O request.