PURPOSE: To provide a optical wiring system which is for monitoring and controlling an elevator, uses a photo-coupler for a photo-stellar type wiring, and can compensate drop of the photo-level caused by photo-coupler divergence.

CONSTITUTION: The 1:N communication is conducted between a centralized monitoring/control device 1 for an elevator and each terminal unit 2 such as a push-button panel installed on Nth floor, wherein photo E/O, O/E converter 3 in one set with the device 1 is furnished. Therein an optical fiber 5 to meet the condition R2xn2>650 is used to compensate drop of the photo-level resulting from diverging with a photo-coupler 4 when an optical signal is N-diverged by the photo-coupler 4 and transmitted to each terminal unit 2 through the optical fiber 5, provided that R represents outside diameter of core and (n) does aperture number (N, A).