Abstract: A channel control system for a scattered loop type information transmission channel has posts that are linked in a single loop and are served both ways by the same loop. Each post consists of an A-system working in one direction and a similar B-system working in the opposite direction. A mode switch circuit switches between a relay mode for relaying the signal and a terminal mode for separating the A and B systems and returning the signal. Each system has a detection circuit for detecting a channel carrier signal OFF and a carrier ON-OFF signal transmission circuit and a monitor circuit for approach and circulation of the channel code. The mode switch circuit of a post which has detected a channel carrier signal OFF switches to the terminal mode and returns a carrier ON-OFF signal, while a post which has detected a carrier ON-OFF signal switches to the terminal mode and continues to issue a second carrier ON-OFF signal.