PURPOSE: To attain monitor and control of numerical information without a time lag by sending the numerical information independently of constant period transmission when a state of the numerical information is changed.

CONSTITUTION: In the power system monitor control system making up of a power system input device 2 receiving a power system state from a remote supervisory controller 4 and plural equipments 3 coupled distributingly to the power system input device 1 via a transmission line 5 and receiving numerical information representing a system state sent periodically from the power system input device 2, the power system input device 2 is provided with a database 114 storing information defining a state change transmission of numerical information, a power system input means 19 discriminating the presence of a state change of the numerical information received from the remote supervisory controller 4 by referencing the information of the database, and a numerical information state change transmission means 15 sending the numerical information to the equipment 3 being a receiver side via the transmission line 5 independently of the constant period transmission when the power system input means 19 discriminates the state change in the numerical information.