The detection of high-resistance grounding faults in DC electric railways is difficult due to the impossibility of distinguishing fault current from load current in such systems. We therefore propose a new detection method to distinguish fault current from load current using the total feeding current of two substations. The technique takes advantage of the fact that the average load current is different from the average fault current. First, this paper describes the new method of detecting high-resistance grounding faults by using the total feeding current, then evaluates the length of time required for detection by simulation and shows the experimental results.