To provide a method for intermediate post-branching in which the easiness of a downward extending work is taken into consideration, a method for downward extending work and a closure used for the work.

The method for intermediate post-branching is characterized by the fact that the length of a peeled-off part 13 of the sheath of an optical cable 8 is longer than that in a conventional method, 75 cm for example, a coated optical fiber which is taken out to be branched is cut in the vicinity of the central part of the optical fiber, the end part of one side 14 of the cut coated optical fibers and the end part of an coated optical fiber 18 of a drop optical fiber which has a sufficient allowance in length are spliced by fusion. The method for extending downward work is characterized by the fact that the part 16 of the coated optical fiber spliced by fusion is left uncut, the drop optical fiber 17 is removed by cutting the coated optical fiber in the vicinity of the end part 19 of the peeled part of the drop optical fiber, and the end part of coated optical fiber on which the part 16 spliced by fusion is left an the end part of the other coated optical fiber 15 which is cut at the time of intermediate post branching are spliced by fusion. The closure is used for the method for intermediate post-branching and has a sleeve of which length is 80 cm or larger.