To immediately alter a rod No. without disassembling a mold by inserting dot bars vertically movably into respective many dot holes formed at a molding position of a mold, and detachably arranging a plate having predetermined protrusions for vertically moving the bars on a surface.

A dot member 4 formed with many hot holes 3 is fixedly arranged on a lower surface of the molding 2, and dot bars 5 are inserted vertically movable into the respective holes 3. Then, a lettering plate 5 brought into contact with lower ends of the bars 5 is provided, and protrusions 7 for slightly rising the bars 5 corresponding to a symbol or a character to be displayed on an upper surface of the plate 6 are projected from the surface of the plate 6 to be slidably drawn from or inserted into the holes 3. That is, the plate 6 having the protrusions 7 for slightly lifting the bars 5 corresponding to the symbol or the character to be displayed is inserted from a lateral direction. The protrusions 7 slightly rise the corresponding bars 5 at a stopping position. Accordingly, the corresponding dot symbol, character or the like corresponding to the plate 6 is displayed on the molding 2.