PURPOSE: To provide a weeder in a simultaneous puddling and planting machine so as to shallowly puddle a plowed field while cutting weeds, embedding the cut weeds in soil and removing the weeds and simultaneously carry out the planting.

CONSTITUTION: This weeder in a simultaneous puddling and planting machine is provided by arranging plural planting units at an interval in the transverse direction at the rear of a mobile machine body, transversely installing a forcedly rotated and driven puddling rotor 15 in front of the planting units and further transversely providing a cutting mechanism 24 with a prescribed interval from the puddling rotor 15 in front of the puddling rotor 15.