PURPOSE: To make a rotary binding unit one revolution using a reasonable construction by providing a clutch in a rotation transmitting mechanism for a stopper engageable and disengageable from the rotary binding unit and the binding unit.

CONSTITUTION: Grain culms, cut by a cutting blade and transversely fed by a conveyor 8 are held at the lower end thereof in a grain culm storing part 10 and the ear tip sides are held by a rotary binding unit 11. When the amount of the grain culms is increased to attain a prescribed value, a stopper 31 is pulled to disengage from the binding unit 11. Thereby, the binding unit 11 is slightly rotated by the own weight thereof to make one revolution by a clutch mechanism provided in a clutch case 15. The binding unit 11 is then stopped in the original state by the stopper 31.