A control system includes a control unit configured to control a control object and communicate with an external device, and a relay unit configured to relay access from the external device to the control unit. The relay unit includes a reception unit configured to receive an authentication request from a request source, an authentication unit configured to authenticate validity of the request source upon receipt of the authentication request by the reception unit, and an access management unit configured to control a restriction level of access from the external device to the control unit when the validity of the request source is authenticated by the authentication unit.

A control system includes a control unit configured to control a control object and communicate with an external device, and a relay unit configured to relay access from the external device to the control unit. The relay unit includes a reception unit configured to receive an authentication request from a request source, an authentication unit configured to authenticate validity of the request source upon receipt of the authentication request by the reception unit, and an access management unit configured to control a restriction level of access from the external device to the control unit when the validity of the request source is authenticated by the authentication unit.