PURPOSE: To make possible to work under preventing damage of crop due to a steering wheel to a minimum by always dividing crop on the traveling route by making a detour to left and right with operated detouring or route- changing action of the steering wheel in a grass divider.

CONSTITUTION: In an agricultural working machine of riding type installing an agricultural working machine 4 on a traveling car body 2 composed of steering wheels having one or both of front wheels 13 and rear wheels 15, grass dividers 42.42 detouring to left and right with operated detouring or route- changing action of the steering wheels are installed in front of the steering wheels. Thus, crop P on the traveling route is always divided and the working is performed under preventing damage of the crop P due to the steering wheels 13 to a minimum as the car body is detoured to left and right by operated detouring or route-changing action of the steering wheels 13.