MANUFACTURING METHOD AND MANUFACTURING DEVICE FOR LADDER CORD OF HORIZONTAL BLIND

PROBLEM TO BE SOLVED: To provide a manufacturing method and a manufacturing device for a ladder cord of a horizontal blind, capable of appropriately adjusting an interval of vertically adjacent middle stage cords in a pair of vertical cords.SOLUTION: The manufacturing method includes: a step of pulling a ladder cord 10 into a thermal processing device 24 while keeping a tension state; a step of heating and molding the ladder cord in the thermal processing device so that the intervals of the vertically adjacent middle stage cords are the same in the pair of vertical cords; a step of pulling out the heated and molded ladder cord from the thermal processing device; and a step of pressurizing one of the pair of vertical cords of the ladder cord pulled out from the thermal processing device. By adjusting tension imparted to the vertical cord by pressurization, any one of the ladder cord 10 for which the intervals of the vertically adjacent middle stage cords in the respective vertical cords are different and the ladder cord 10 for which the intervals of the vertically adjacent middle stage cords in the respective vertical cords are the same is manufactured.