To detect the consumption of a wire through the revolution of a reel.

An interrupter 65 is fitted on a cassette case 60 of a binding machine body 21. In the cassette case 60, a cover 66A is held in a revolvable manner, and openings 70 are formed on the cover 66A. Projections 74A are formed on the reel 61 and are fitted into the openings 70, respectively. The distance of the projections 74A and of the cover 46 from the interrupter 65 are varied, respectively, to vary the volume of reflective light received and detected by the interrupter 65, thus fluctuate the output of the interrupter 65 to detect the revolution of the reel 61 through the output fluctuation.