PURPOSE: To enable the machine side to select and supply appropriate information in response to the state of the man side that receives the information, by detecting and discriminating the state of an operator and selecting the information to be supplied based on the result of said discrimination.

CONSTITUTION: The state of an atomic power plant is converted into electric signals by a detector and supplied to a central processor 31 via a process input device 41. A data processing part 314 monitors an alarm and produces an operating guide for other operators. While the signals given from an electroencephalograph, a tonometer and a pulsimeter serving as the state detectors for operators are supplied to the processor 31 via a process input device 25 and processed by a process input processing part 311. Then an operator state deciding part 316 decides the present operating state of the operator. A supplied information selecting part 317 processes the CRT display information delivered to a CRT controller 43 in response to the consciousness level of the operator obtained from the part 316 and delivers the information of an appropriate form.