PURPOSE: To obtain a device capable of randomly inserting a heald to a heald retaining rail without taking care of a left and right bending state of heald, automatically inserting into a heald bar in a desired bending direction in spite of improvement in efficiency of insertion operation and extremely increasing operation efficiency.

CONSTITUTION: In separating a heald 1 located at the tip of a heald retaining rail 3 from the heald retaining rail 3, detecting the bending direction of the heald 1 and then placing the heald 1 on a weft threading part, the bending direction of the heald 1 is changed only when change of the blending direction is required based on detected information of the bending direction, the heald 1 is placed on a weft threading part and warp is inserted to the heald 1. Then the heald is inserted into a given heald bar 2.