PURPOSE: To obtain a comparatively simple speedometer capable of discriminating the advance movement of a vehicle and its retreat movement.

CONSTITUTION: This speedometer has sensors 13 from first to N-th which respond to energy inputted from the continuous regions from first to N-th of an object, and measures the velocity to the object. In order to delay the signals from sensors from second to N-th, signal delay means 21-27 are installed. The delay is increased as the sensor number increases. A substractor 16 is installed and forms the difference between the sum of signals from even-numbered sensors and the sum of signals from odd-numbered sensors.