To obtain a molding method in which an old material of a covering layer is replaced quickly with a new material by extrusion-molding lengthy moldings continuously.

The molding method for the lengthy molding having the covering layer on the surface includes a process for extrusion-molding a lengthy molding main body and a successive process for forming the covering layer by a covering layer forming apparatus. In the process for forming the covering layer, when a signal indicating that a product having a different covering layer is molded by the covering layer forming apparatus is sent from an extrusion molding controller, the change-over valve 30 of the covering layer forming apparatus is changed over, and a covering layer 57 made of a different extrusion molding material is extrusion-molded on the lengthy molding main body 51 while the lengthy molding main body 51 is conveyed continuously.