In Japan, many surge arresters have been installed on 6.6 kV overhead distribution lines for reducing lightning overvoltages. The increase of surge arresters has resulted in a remarkable decrease of lightning outages of distribution lines caused by insulator flashovers. In contrast, several surge arresters have been damaged by direct lightning strikes to distribution lines. Studies of countermeasures for the failure of surge arresters are generally carried out by lightning surge analysis using the Electro Magnetic Transients Program (EMTP). In the previous studies, a simple model of a straight line is used, however, branch lines and termination points also exist in the actual distribution lines. In this paper, we present the influence of configuration of distribution lines on the failure probability of surge arresters obtained by the lightning surge analysis.