PURPOSE: To accurately convey information regarding slipping states to a driver by detecting an acceleration slipping state by comparing a driving wheel speed signal obtained from the rotating speed of a drive shaft with a vehicle body speed signal obtained from the acceleration of a vehicle body.

CONSTITUTION: When an acceleration pedal 15 is pressed and an acceleration pedal switch 6 is turned on from a stopping state, a timer counter 7 starts counting and the signal of a rotating speed sensor 2 is converted into the speed of driving wheels by means of the 1st speed converting section 8. On the other hand, the signal of an accelerometer 4 is converted into the actual speed of the vehicle body by means of the 2nd speed converting section 10. The driving wheel speed signal is inputted to a comparator 13 through a subtraction circuit 12 where the signal is subjected to subtraction and the vehicle body speed signal is inputted to the comparator 13 through a speed limiter section 11. The comparator 13 outputs the difference between the speeds as a potential difference and displays a slipping rate by turning on LEDs 14. Therefore, the information regarding the state of acceleration slipping can be conveyed accurately to a driver at the time of departure.