Provided is a subject device comprising: a control permission issuance part for issuing a new control permission each time a control permission issuance request is received from any of a plurality of control devices, and for returning information of the new control permission to the control device having transmitted the issuance request; a control permission management part for managing the control permissions such that only one among the issued control permissions is valid and the other issued control permissions are invalid; and a mutual exclusion part for, upon receipt, from any of the plurality of control devices, of a control commencement request to which the information of the control permission has been appended, verifying whether the control permission appended to the control commencement request is valid, allowing exclusive control by the control device having transmitted the control commencement request if the control permission is valid, and denying control by the control device having transmitted the control commencement request if the control permission is invalid.