Abstract: A hair bundling core structure comprising an elastic cylinder made of a foamed synthetic resin having a thickness and a strength which are sufficient for facilitating the insertion and extraction of a hair setting U-shaped pin and are capable of fixing the hair by the insertion. The core structure is cut from one end face to the other thereof to have a rift.

Abstract: A hair bundling core structure comprises an elastic cylinder for letting a hair bundle to pass therethrough, which cylinder is split by a rift, and a hair fastening pin connected to a lower end portion of the elastic cylinder by an attachment member at a side opposite to the rift. The hair fastening pin has a plurality of shafts for thrusting into the hair bundle and is allowed to move between a first position in which the shafts tend parallel to an axis of the elastic cylinder and a second position in which the shafts tend perpendicular to the axis. The elastic cylinder is formed of a foamed synthetic resin having a thickness and strength which are sufficient for facilitating an piercing of a hair fixing U-shaped pin and an extraction of the same from the elastic cylinder.