To prevent breakage of a rotary shaft part to be rotated so as to adjust a height dimension of a blind.

A lower end of a ladder cord 14 suspended from a head box 12 to support many slats 16 in an aligned state is connected to a bottom rail 24 by a holder 30. The holder 30 includes a holder body 32 locked to the bottom rail 24 and an adjusting member 34 supported by the holder body 32. The adjusting member 34 is provided with a rotary shaft part 34a to which the lower end of the ladder cord 14 is fixed, and the lower end of the ladder cord 14 is wound around a cylinder part 32a of the holder body 32 or the rotary shaft part 34a. A radial direction dimension of a distal end 34h of the rotary shaft part 34a is smaller than the part where the ladder cord 14 is wound, and when the ladder cord 14 starts to be wound around the distal end 34h, the action of getting over the distal end 34h of the small diameter acts, and the ladder cord escapes from the wound part.