PROBLEM TO BE SOLVED: To solve the problem wherein reliability of protections of signal facility, etc. of a railroad is lowered or maintenance or inspection work is complicated by a damage due to life shortening due to a dynamic current phenomenon and an excess surge generated at an insulation space passing time of a train.
SOLUTION: In a safety device for an electric railcar line which absorbs excess voltage through an electric railcar line for supplying the power to the electric railcar EC, a main discharge cap G2 is arranged between a negative feedback line NF of a return circuit and a protective ground wire FW or a ground, and a safety device H connected in parallel with a subdischarge cap G3 is arranged in a series connection circuit of a gas arrester h5 and a resistor h2 or in a gas arrester of a series connection circuit of the gas arrestor and a resistor. Thus, the dynamic current by electric discharge of surge voltage generated when a train passes through an insulating space is prevented, and the discharge operation is certainly performed even at a ground-fault accident time. Further, gap adjustment of the discharge gaps after they are arranged, is not needed.