Annealing furnace, method of constructing annealing furnace, and structure for prefabrication

An annealing furnace that includes a case, and plural rows of rolls at a top and a bottom of an inside of the case, the rolls being configured to convey a steel strip, the annealing furnace comprising:

• horizontally parting faces where a body of the furnace is horizontally divided into horizontally parted sections, wherein
• each of the horizontally parted sections parted by the horizontally parting faces further has vertically parting faces where the horizontally parted section is divided in a direction vertical to a longitudinal direction of the body, wherein
• structures for prefabrication which are parted at the horizontally parting faces and the vertically parting faces each include a secondary member for connecting the vertically parting faces on the structures for prefabrication to each other, and
• a width of the secondary member of one of any pair of the structures for prefabrication to be connected together is different from that of another one of the pair in a horizontal direction.