PURPOSE: To make control by a quantitative tightening force possible by a method wherein a clamping jig with driving teeth, which engages with a saw blade shape protruding part, is inserted in a bundling fixed part, and a bundling band is moved by turning of the clamping jig.

CONSTITUTION: Electric wires C are bundled by a bundling band 1 by winding around the electric wires C once, and the leading end 4 is inserted to a flexible engaging piece 5 side of a band insertion hole 6. When the band leading end 4 which protrudes to the other side of the inserting hole 6 is pulled downward by hand, a saw blade shape protruding part 2 transfers by ratchet system while coming into contact with a saw blade shape protruding part 5a of the flexible engaging piece 5 to tighten the electric wires C, and a temporarily tightened condition is completed. Then, a driving rod 8 of a clamping jig B is inserted in a clamping jig insertion hole 7, a driving gear 9 is engaged with the saw blade shape protruding part 2 of the bundling band 1, and an operation rod 10 is moved in the vertical F direction. By doing this, the saw blade shape protruding part 2 is sent downward G by the driving gear 9, and the flexible engaging piece 5 follows by ratchet, deflecting for each protuberance. Then, when the operation rod 10 is pulled down, the driving gear 9 moves to the right by a small clearance of the clamping jig insertion hole 7, and gives an idle run. Thus, by the vertical motion of the operation rod 10, the saw blade shape protruding part 2 is sent downward gradually, and the electric wires C are tightened.