Abstract: A binding device for binding the openings of bags or the like which is small and simple in structure but effective in operation without requiring an electric power source. The binding device comprises: a stationary vertical support plate carrying a reel of binding material, a pair of rocking plates pivotally secured to the support plate, a cord delivery mechanism having a pair of supporting rollers, a cord winding mechanism having an actuating rod, an actuating plate and a pair of winding arms, a cord cutting mechanism, and a cord twisting mechanism having an engaging pawl to twist the end portions of a cut cord piece together.