Abstract: Bag tying apparatus for tying bags with a resilient tie. The apparatus comprises a tie wrapping plate and a tie twisting mechanism. The tie wrapping plate is linealy movable. The plate has a stepped groove which extends in the moving direction of the plate and an elongated recess which runs across the stepped groove. The resilient tie is placed on the bottom of the elongated recess, and bag is so positioned that its gathered neck to be tied is placed above the tie wrapping plate. As the plate is moved up by an air cylinder unit, the gathered neck of the bag is caught in the stepped groove of the plate. As the gathered neck of the bag enters the narrow section of the stepped groove, the resilient tie is gradually bent and finally substantially U-shaped.The tie twisting mechanism comprises a twist shaft, a pair of twist hooks fixed to the lower end of the twist shaft, and a sprocket wheel secured to the upper end of the twist shaft.