PURPOSE: To improve the riding feeling in a train, to save energy and to improve the running speed of the train as well as to prevent unnecessary slip of the train without forcibly decelerating the train more than required by controlling the brake force by an ATC in response to the excessive acceleration.
CONSTITUTION: In an ATC, a speed difference detector 6 detcts the indicated speed difference of received signals before and after the alternation of the speed and outputs it as speed difference information V1-V2 to a speed excessive rate detector 8. An excessive speed rate detector 7 inputs indicated speed informaion from an indicated speed detector 2 and train speed information from a tachometer generator TG, detects the situtation when the train speed exceeds the indicated speed, outputs ATC brake instruction information to a brake indtruction unit 10, calculates the excessive speed to the indicated speed when the signal is altered, and outputs it as excessive speed information ΔV to the detector 8. The detector 8 divides ΔV by the information V1-V2, thereby detecting the speed excessive rate and outputs the detected information to a brake force detector 9. The detector 9 outputs the information as brake reduction rate information to the commavd unit 10.