PURPOSE: To collect contact information to be monitored even at the site where there is no electric power source by starting a battery by the contact information to be transmitted, operating a transmission terminal having a photoelectric conversion function, and transmitting the information through an optical fiber.

CONSTITUTION: A contact point switch 2 is operated by a contact point information 5 of such as a limit switch, etc., to start a battery 4 and an electric power source is supplied to a timer relay 3 to operate a transmission terminal 1. The information put in the transmission terminal 1 is converted into an optical information and the information is transmitted as the optical information to a monitoring apparatus at a remote site through an optical fiber cable 6. Here, to prevent the consumption of the battery 4, even if the information 5 comes for a long duration, the operation time of the timer 3 is set to be a short time.