The utility model provides a needle bending device for a sewing machine. The needle bending device is improvement on the structure of a needle bending groove of a pipe which is arranged on a bent needle of an overedger and used for assembling and bending needles and threading, the pipe is easy to manufacture and the production rate of the bent needle with a threading pipe is improved. An upper bent needle (7) is provided with the needle bending groove (36) for assembling the pipe (29); the needle bending groove (36) is provided with a needle bending groove bending part (Cg1) and needle bending groove linear parts (Lg1/Lg2) which correspond to a needle bending part (Cp1) and pipe linear parts (Lp1/LP2); and the groove width (Wg1) of the needle bending groove bending part of the needle bending groove is greater than the groove widths (Wg2) of the needle bending groove linear parts.