A bi-directional path switched ring optical transmission node has simple configuration which reduces the influence of a wave reflected by an obstacle on optical line.The BPSR optical transmission node connects to a first optical line through which an odd channel signal and an even channel signal are transmitted to and from the BPSR optical transmission node in direction opposite to each other. The BPSR optical transmission node further connects to a second optical line through which the odd channel signal and the even channel signal are transmitted from and to the BPSR optical transmission node in direction opposite to each other. The BPSR optical transmission n-ode includes a node section for directing the odd channel signal and the even channel signal, dropping/adding a desired channel from/to the odd channel signal and the even channel signal,and then allowing each of the odd channel signal and the even channel signal to proceed in a direction traveled by that channel signal upon arriving at the BPSR optical transmission node; and filtering section coupled between the node section and respective optical lines, the filtering section allowing only one of the odd channel signal and the even channel signal to pass without attenuating the signal.