To efficiently form a narrow topping sheet. The invention relates to a topping sheet forming method that includes: a division step of cylindrically winding a textile original fabric (100), obtained by weaving longitudinally aligned tire cords (101) into a cord fabric by use of weft yarns (102), to form an original fabric roll (100R) and cutting off the weft yarns (102) in predetermined widthwise positions by using a wire (71) wound on the original fabric roll (100R) in a predetermined winding angle range to divide the textile original fabric (100) into narrow textile original fabrics (100S); and a topping step of topping at least one surface of each of the narrow textile original fabrics (100S) with unvulcanized rubber.