To prevent the collapse of an accumulation condition at the time of discharge so as to improve an operation rate of the whole book binding system by controlling a position where a discharge bar comes into contact with a finished book, a discharge speed after the contact, and a discharge position to the next process in accordance with sizes of the finished books independently and freely.

Since control shafts (7), (8) of discharge means 7, 8 are independently provided from a control shaft (2) controlling a pushing out plate 21 of a bound book W, it is possible to drive the discharge means independently from a position of the pushing out plate 21, and cycle time of the whole automatic three-way cutter 10 is not limited. Moreover, since forward and backward positions of discharge bars 71, 81 and travel speed can be controlled freely, the discharge bars 71, 81 can be brought into contact with a position of just back part of a finished book P in accordance with a dimension of a small diameter of the completed product so as not to give a shock. Since proper travel speed at the time of discharge is obtained, the collapse of an accumulation condition of the discharged and finished books P is eliminated, and a rate of operation is improved.