In order to assess the genetic usefulness of feces that were obtained from field, we conducted genetic identification by microsatellite analysis on fecal samples of the red fox (Vulpes vulpes) collected in the Shiretoko National Park, Hokkaido. Consequently, 59 fecal samples resulted in 22 as the minimum number of individuals. The cumulative P_(ID)sibs in the 22 samples was less than 0.01. Two pairs of fecal samples having the identical genotypes (P_(ID)sibs < 0.01) were considered to be dropped by the same foxes, and the distribution of these feces was almost overlapped with the home range of one fox, revealed by a previous study. Although few reports had revealed the absolute number of red foxes in field, the present study showed that the genetic analysis of their feces is useful for estimating a presumable number of individuals in the area. However, the lower genotyping success rates (23.3–69.8%) and genotyping reproducibility (53.5–88.4%) indicate the difficulty of genetic analysis by using these fecal samples. In order to improve the efficiency of the analysis, it may be effective to select and use a marker set which has smaller allele sizes, because the genotyping success rates and reproducibility increased when the average allele size decreased.