This paper dealt with the performance evaluation and the diagnostic techniques of lightning arresters for DC electric traction vehicle. Field Measurements on the protective operation of lightning arresters against surge currents were carried out on running vehicles to acquire the data necessary for the diagnosis. The frequency and the magnitude of surge events were analyzed. Surge currents of $1sim3$ times were recorded in one running service route and their magnitudes were ranges of $150Asim2kA$. Also, an acceleration experiment on a lightning arrester by the standard lightning impulse current of 8/20 us and 5 kA was performed to know the aging characteristics. After the surge current application of 3,000 times, the reference voltage decreased by 4.5 %, and the leakage current was below 10 uA at the continuous operating voltage and about 50 uA at the rated voltage. From the experimental results, we propose a decision level of leakage current for the arrester used in this paper and designed an arrester tester which analyzes arrester condition by the magnitude of leakage current.