To prevent a working device from being automatically lifted and driven in the course of a working stroke and operations from being discontinued in a structure for lifting and lowering the working device of a paddy field working machine equipped with an automatically lifting means for automatically lifting and driving the working device when front wheels are steered and operated from the side of a directly advancing position to the right or left.

This structure for lifting and lowering the working device is equipped with a travel distance detecting means for detecting the travel distance J1 of a working stroke K1 at a time from either one G1 of ridges to the other ridge G1 in a field and a judging means for judging whether or not the working strokes K2 and K3 at a time are nearly completed on the basis of the detected travel distance J1. Thereby, the operation of the automatic lifting means is interrupted if the working strokes K2 and K3 at a time are not kept in a nearly completed state.