The present invention relates to a prefabricated bobbin having a polygonal geometry; Pull is wound in the mandrel and mandrel assembly is radially disposed for supporting the plurality of seolju and the seolju, jjong bobbin made as passing through the center of the mandrel assembly; The seolju has fitting hole is formed, and an end of the mandrel, the assembly and is formed with a fitting protrusion fitted in the fitting hole; The seolju is formed with the first fastening holes in communication with the ball and the fitting, the fitting protrusion of the mandrel are formed second engaging holes corresponding to the first coupling ball is characterized in that the spring-loaded pin fastening. Prefabricated bobbin having a polygonal structure according to the invention is formed of a ball-fit fastening of claim 1, which ball and communicates formed seolju, the second fastening the fitting protrusion which is provided on an end of the mandrel holes are formed spring pins is entered into a separate adhesive If it without the use of a solid is also seolju and the fitting projection assembly is possible, while removing the spring pin it can be easily disassembled.