In a fusion splicing method and device for optical fibers, bare fibers (f) of ribbon optical fibers “F” to be spliced together are arranged, in opposite direction to each other, on a fiber setup stage (30). An interval of a pair of the discharge electrode rods (10,20) is optionally changed according to the fiber number of the bare fibers “f” of the ribbon optical fiber “F” so that all of the bare fibers “f” are set into a uniform temperature area in a discharge area, and an optimum fusion splicing process is performed according to the fiber number of the bare fibers “f”.