In Japan, the recent decline in public transport services has increased people’s reliance on motor vehicles, especially in rural areas. Older adults are no exception. Despite their importance to the daily lives of older people who do not have their own vehicles, many public transport services have ceased operation or had their numbers of routes reduced (e.g., buses). Thus, with the aging of the population, traffic accidents caused by older people have become increasingly common. In order to reduce the frequency of such accidents, we need to clarify the relationship between traffic accidents and the convenience of public transportation. Therefore, using municipal panel data on the numbers of traffic accidents, demographic structure, and living environment, we empirically analyze the factors that affect such accidents. The results reveal that (i) the larger the number of population density in a municipality, the lower the frequency of traffic accidents, and (ii) the higher the ratio of older residents in a municipality, the higher the frequency of traffic accidents. Moreover, we find that the number of bus stops and the number of train passengers have negative effects on the frequency of traffic accidents, implying that better public transit services reduces the frequency of traffic accidents.