PURPOSE: To achieve the perfection of the butt connection of high accuracy with low cost by inserting and fitting a pair of plugs to which optical fibers are mounted and fixed, with the marshaling pins of a holding and fixing member as a guide.

CONSTITUTION: A holding and fixing member 9 is provided with the marshaling pins 10 which fit into the recesses between the cylindrical members 12 or cylindrical columnar members which are adjoining with each other. With said marshaling pins 10 as a guide, a pair of plugs 8 in which optical fibers are mounted and fixed to the centers of the cylindrical members 7 are inserted into the holding and fixing member 9 and are butt-connected. Hence, the mutual positions of the plugs 8 are maintained by the pins 10 with good accuracy and giving any connection deviation to the butted optical fibers is obviated.