PURPOSE: To simplify the running speed change control and the working speed change control of a working vehicle.

CONSTITUTION: A speed change controller has a running guide groove 2 which guides a single transmission control 1 so as to allow the control to change vehicle speed and a working guide groove 4 which causes the control 1 to change the speed of a working device 3. The running guide groove 2 is provided with an advance low-speed position L adapted for working speed between an advance high-speed position H and a retreat podition R. The working guide groove 4 is provided with a working neutral position N between speed change positions A, B for the working device 3. A switching guide groove 5 is provided which freely switches the speed change control 1 between the running guide groove 2 and the working guide groove 4 only when the control 1 is located between the advance low-speed position L of the running guide groove 2 and the working neutral position N of the working guide groove 4.