PURPOSE: To provide the active type optical fiber coupler capable of realizing distribution of large electric power signal light with a small size at a low cost and the process for production thereof.

CONSTITUTION: This active type optical fiber coupler is produced by fusing the central parts of at least two pieces of optical fibers arranged in parallel with each other and stretching the fibers to a longitudinal direction, thereby expanding the fibers to a taper shape from the central part to both end sides. The optical fibers 4-1, 4-2 which are not added with rare earth elements within the cores are used from the input side of the optical fibers to a fusion stretched part 2. The optical fibers 5-1, 5-2 which have the plural cores in the clads and are incorporated with the rare earth elements within the respective cores are used from the fusion stretched part 2 to the output side of the optical fibers.