To solve a problem wherein a long stroke causes an operating delay of air and inhibits the speeding up of a binding machine, in which a bag holding claw clipping a bag opening is moved linearly by an air cylinder.

The binding machine includes a binding machine body 12 equipped with a pressure sensitive adhesive tape 6 for binding the bag opening of a packaging bag 4, and the bag holding claw 7 with a pair of freely openable/closable claws 16, 19 for narrowing the bag opening of the packaging bag 4 and the air cylinder 27 for moving to the binding machine body 12 side. The bag holding claw 7 narrows the bag opening of the packaging bag 4 and moves to the binding machine body 12 side while the binding machine body 12 moves in a direction opposite from the moving direction of the bag holding claw 7 so as to receive the bag opening.