In Japan, with the progress of lightning protection measures, lightning outages associated with indirect lightning are less frequent, and direct lightning is the main cause of lightning outages. To achieve an effective lightning protection design for medium voltage distribution lines considering cost performance, it is necessary to evaluate the lightning outage rate for each equipment configuration. As for this purpose, we have developed the lightning outage calculation program for medium voltage distribution lines due to direct lightning. The developed program can estimate not only the flashover rate of insulators and the absorption energy exceeding probability of surge arresters, which have been studied in previous studies, but also the flashover rate between the phase conductors and the energy absorption history of the surge arresters which have not been studied enough. In this paper, we show the outline of the developed program and some examples of calculation results.