To provide a butt end working device in the case of manufacturing a precut which is so constituted as to make it possible to mount the connecting member of metal formed in a cross-like state by providing a notch at the diagonal line of the butt end of a timber.

When a timber is so placed and conveyed as to dispose the one corner of the timber at the center of a conveying roller 6 and the timber is brought into contact with a stopper member 21 so constituted as to protrude above a conveying passage, the timber is clamped by a clamping member. An elevator pedestal 26 that the bearing 25 engaged with the longitudinal rail 24 at the side of a post 23 is fixed to the cylinder mounted at a mounting base 17 is vertically moved. The laterally moving base 30 mounted at the pedestal 25 is driven by a lateral moving cylinder. Notches are provided at the diagonal line of the butt end of the timber at two stages by circular saws 33, 34 fixed to the rotary shaft to be rotated by a motor 31 provided at the base 30. Thus, the timber is so conveyed by the roller 6 that the corners of the timber becomes vertically linear, and the notch can be provided at the diagonal line from the corner, and hence the cut edge is clear with high operating efficiency.