To reliably make a binding structure mechanism exert its function by reducing the number of parts so as to facilitate assembly and making various types of operating means operate smoothly.

An intermediate base plate 30 is interposed between a lower base plate 10 and an upper base plate 60 superposed above the base plate 10, so as to form a base plate-laminated structure 9. Ribs 34 and 44 are provided in peripheral parts of a surface and a backside of the base plate 30 so as to form a space part. In the space part, there are built a guide groove 35 which is required to bind an object 8 to be bound, feed rollers 81a and 81b which brings about the advance of a binding wire guided by the guide groove 35, a cutting means 82 for cutting the binding wire, which is fed from the guide groove 35, to a prescribed length, an applying means 85 for applying the cut binding wire to the object 8 inserted into an insertion part, a twisting means 88 for binding the object 8 by both ends of the binding wire applied to the object 8, and the like. This dispenses with a conventionally required metal spacer, and enables accurate assembly of the operating means and a reduction in friction.