PURPOSE: To smoothly carry out rolling operation based on manual handling and to simplify structure.

CONSTITUTION: In a rolling control device of a working machine wherein a seedling planting device is connected drivably in rolling to a traveling machine body by an electrically-driven motor M and the electrically-driven motor M is automatically controlled in such a way that the seedling planting device takes an objective attitude based on detected information of an inclination sensor, the rolling control device is equipped with a three position shift switch 28 which is returned and forced to a neutral position and is freely changed to operation positions of both a right and a left positions R and L by manual handling. Rolling control operation is allowed only when the switch 28 lies at the neutral position. The rolling control device is checked when the switch 28 is shifted to either the right or the left operation position R or L. When the switch 28 is changed to one operation position R, the electrically-driven motor M is driven in a prescribed direction only during existence in the operation position of the switch and when the switch is shifted to other operation position L, the electrically-driven motor M is driven in the opposite direction only existence in the operation position.