PURPOSE: To prevent a photoconductor rod from sliding down by interposing a transparent spacer between photoconductor rods run through pipes and clamping a supporting arm provided to the peripheral part of the spacer with flanges of the pipes.

CONSTITUTION: When the optical waveguides which have photoconductor rods 101 and 102 run through the protection pipes 111 and 112 are connected vertically to each other, the transparent spacer 20 which has nearly the same diameter with the photoconductor rods 101 and 102 is interposed between the photoconductor rods. This spacer 20 has arcuate cut parts in the peripheral part at plural positions and engages the transparent supporting arm 21 which has cut parts engaging said cut parts and extends toward the protection pipes 111 and 112. This supporting arm 21 is clamped between flanges 141 and 142 engaged with the protection pipes 111 and 112 threadably through a packing 30.