PURPOSE: To make it possible to perform combination use with accelerator pedal operation in simple composition by providing a piston and sheave mechanism halfway on the cable connecting a throttle lever and accelerator pedal.

CONSTITUTION: When wheel acceleration slip starts to occur, a control pressure device supplies a piston 4 with control pressure by wheel acceleration signals. Then, the piston 4 works to push back a throttle lever 1 for reducing driving force, and as a result slip is cancelled. In the case where the accelerator is slightly operated, when the piston 4 moves, a balance spring 11 will not be deformed and the tension of a cable will not changed, which returns the accelerator pedal 5 along with the motion of the piston 4. On the other hand, in the case where the accelerator 5 is largely operated, the balance spring 11 will be deformed along with the motion of the piston 4 for letting a running block 8 return. As a result the cable 2 will loosen, and the throttle lever 1 will be returned, however, the accelerator lever will not be returned.