To provide a binder capable of adhering overlapped both end portions of a binding material in a superior manner with a specified pressing strength even if a certain dispersion occurs in heights of bundled groups or their hardness.

The binder comprises a catching unit for use in binding a large band on a binding group and overlapping both ends of the band on the binding group; an adhering device 47 for pressing movable blocks 51, 51 against both ends of the large band wound and overlapped by the catching unit to adhere both ends of the large band; a lower part detecting sensor 55 for use in detecting a displacement of each of the movable blocks 51, 51 when the blocks are displaced from the pressing position at the time of pressing of the blocks; and a control means 60 for controlling an operation of the adhering device 47 in such a way that the movable blocks 51, 51 press again against both ends of the large band on the basis of the detection of the lower part detecting sensor 55 for the displacement of the movable blocks 51, 51.