To provide a knotter having a buffer device with which impact force of a packer is relaxed and occurrence of vibration or noise is prevented and it is regularly carried out to rake discharged straw even when a link arm supporting the packer attains the top dead center or the bottom dead center of a swinging locus.

This packer of knotter for combine harvesters is obtained by disposing a spring (7) between a packer (1) drawing a swinging locus (2) and the link arm (3) connecting to the packer (1), applying a spring pressure to the packer (1), making spring pressure which occurs on a return side (4) of the swinging locus (2) higher than that of the acting side (6) of the locus (2) and keeping the pressing state of the spring (7) in the process ranging from the top dead center (8) to the bottom dead center (X).