The objective of this study is to develop ¡ÇVirtual Collaborator¡Ç as a new type of human-machine interface, which works as ¡Çintelligent interface agent¡Ç to help machine operators controlling large scale machine system such as power plants. In this paper, first, the basic concept of the virtual collaborator is introduced. And, the prototype system of the virtual collaborator is described. At present, the prototype system has no communication function, however, when an anomaly occurs in a virtual nuclear power plant, the virtual collaborator can detect it, diagnose the root cause, and operate the control panel in accordance with emergency operation procedures, autonomously. Then, in order to realise bi- directional communication as the next step, the framework of ¡ÇAffective Interface¡Ç is introduced. The affective interface is a human machine interface system, which deals with ¡ÇAffective Information¡Ç to realise smooth communication between human and machine.