In an end sealing step, an end is sealed by which the core material of the end of a spring member is gathered by machining. For example, a squeezing roller is moved in an axial direction as necessary, while the end of the spring member is pressed to the inside in a radial direction by the squeezing roller. As a result, the end of the spring member is sealed and therefore, it is not necessary to use another member such as a lid member. For example, the end sealing step can be immediately carried out after an inner surface processing step. In a coil forming step after the end sealing step, formation of clearance can be prevented at the end even if the end of the spring member is gripped and the spring member is wound around the rod.