A riding rice transplanter as an example of traveling agricultural machines has a traveling body (2) supported by wheels (5, 6), an engine (7) mounted on the traveling body (2), a traveling transmission (8) for changing the speed of the engine (7) and transmitting the changed speed to the wheels (5, 6), and a shift pedal (12) for controlling the traveling transmission. The rotational speed of the engine (7) is controlled by an accelerator lever (7a). The shift pedal (12) and the accelerator lever (7a) are interlocked by a cam means (37). When the shift pedal (12) is depressed, the rotational speed of the engine (7) is increased, and when the shift pedal (12) is returned, the rotational speed of the engine (7) is decreased. When the engine (7) is set to a high rotational speed range at the beginning of the depression of the shift pedal (12) and then gradually accelerated, smooth operability of traveling, good working efficiency, and high-speed operation of the rice transplanter are realized with quietness and fuel cost saving of the rice transplanter when the rice transplanter is at a stop achieved.
