PURPOSE: To facilitate operation for moving a Jacquard machine body, guide board and base using a weft-inserting side as a base while fixing the position of a weft-inserting main nozzle when woven width is changed.

CONSTITUTION: The number of harness cords 25 is increased or decreased to the number necessary for woven width after change, while a motor 53 is positively or reversely driven. Thereby, a vertical member 51 is moved downward or upward and first, second or third lateral members 41 to 43 interlocks a Jacquard machine body 21, guide plate 2 and base 23 through pinion gears 47 to 49 along a rails 28, 29 and 31 simultaneously and by same distance to weft-inserting side and anti-weft-inserting side. Thereby, the position of Jacquard machine body 21, guide plate 22 and base 23 are accurately controlled using the weft-inserting side as a base.