The present invention relates to a core for hollow product manufacture including a multilayer filling material, which may be used in forming a cooling water circulation channel through which a fluid such as cooling water may pass, and a method of manufacturing a hollow product using the core, and the core includes a pipe, having a hollow formed in the pipe and an opening formed at both ends of the pipe so that the hollow is exposed to the outside through the opening, a first support member, being disposed inside the hollow and having a space formed in the first support member, a second support member, being disposed in the space, and a melting bar, passing through the second support member in a longitudinal direction of the melting bar, wherein the melting bar melts and forms a space in the second support member when the melting bar is heated.