PURPOSE: To enhance operability by calculating the amount of discharged papers to set the length of a binding needle and selecting the binding part equipped with the set binding needle from binding parts to send the papers to a paper post-treatment apparatus to bind the same.

CONSTITUTION: A hopper 16 storing the papers 4 supplied to a recording apparatus 2 in a stacked state and a paper post-treatment apparatus 17 equipped with a plurality of binding parts 5a-5d collecting the papers 4 delivered from the hopper 16 and recorded in the recording apparatus 2 to automatically bind them are provided. The binding parts 5a-5d are respectively equipped with binding needles different in length and a paper pressing means 11 correcting the pressure between the papers 4 reduced by delivery and a delivery roller 10 and a microprocessor 19 equipped with a detection means detecting the operation quantity of the paper pressing means 11 are provided to the hopper 16. The amount of the papers 4 discharged on the basis of the data of the detection means is calculated to set the length of a binding needle and the binding part equipped with the set binding needle is selected from the binding parts 5a-5d to send the papers 4 to the paper post-treatment apparatus 17 to bind them.