A optical fiber coupler manufacturing device is disclosed for the manufacture of fused-elongated type optical fiber couplers. The disclosed invention provides an optical fiber coupler manufacturing device having a chassis, a pair of movable stands provided within the chassis forming a space therebetween, optical fiber mounting units for mounting and fixing two or more component optical fibers on the above mentioned pair of movable stands, and a drive mechanism whereby the pair of movable stands can be driven back and forth in a direction parallel to the longitudinal axes of the component optical fibers. By virtue of the space formed between the two movable stands, a heat source can be applied to the aligned portions of the component optical fibers, thereby effecting thermal fusing of the aligned portions, after which drawing out of the thus fused section can be effected using the above mentioned drive mechanism for the movable stands, and additionally, a protective case for surrounding and reinforcing the manufactured optical fiber coupler can easily be applied without removing the optical fiber coupler from the apparatus through the above described space.