To improve fixing force to a packaging bag by a horseshoe plastic clip rich in elasticity, that is, to solve a problem that ends of the plastic clip are easily opened due to their elastic characteristics resulting in fastening force loosened, when a bag mouth is fastened by making the horseshoe clip into a ring by impressing impact.

The horseshoe plastic clip 11 comes forward with a bag mouth of a packaging bag 15 held in the clip and binds the bag mouth 15 for fastening as the clip is formed into a ring along an arcuate surface 20 of a clincher 14. A drill tip projection 16 toward the clincher 14 is formed at the center of an internal surface of the clip. A ring diameter of the clip 11 is reduced to cause the projection 16 to stick through the bag mouth 15, whereby the bag mouth 15 is prevented from removing from the clip 11.