Abstract: The rod assembly for wafers comprises a plurality of rods, made of materials to be used as the wafers used for electronic devices which are assembled in parallel and bonded with each other into an integrated body. Wafers used for electronic devices can be obtained by slicing the rod assembly for the wafers. Mirror-finished bonded face is formed to the outer surface for each of the rods. The bonded face to each of the rods is cleaned by a surface treatment using chemicals. Subsequently, respective rods are assembled in parallel and brought into contact with each other at their respective bonded faces. The thus prepared rods are maintained in a heated atmosphere into an integrated body. Then, the rod assembly is applied with slicing for providing wafers used for electronic devices. Since the rod assembly has a structure in which a plurality of the rods are assembled in parallel and bonded with each other into an integrated body, the diameter for the rod assembly can remarkably be increased.