We studied the factors affecting distribution of terrestrial blood-feeding leeches, in particular the distribution of their host mammals in Yakushima. Data were collected in August 2010 and 2011. Abundance of leeches and mammals were studied by point census: when the observers arrived at the observation point, they removed all the leeches on their bodies. After three hours, they counted the number of leeches attached on their bodies, which was used as an index of leech abundance at that point. Group density of macaques and the number of deer fecal pellets in the 4 m*50 m transect established near the points were used as indices of monkey and deer abundance, respectively. In total, leech count was conducted for 194 point·days in 2010 and 174 point·days in 2011 at 30 points. Effects of vegetation, road, abundance of deer and macaques in the current and previous years on leech abundance were analyzed using GLMM, using observation day as a random factor. The best-fit model in 2010 included road and the deer distribution in the previous year. The best-fit model in 2011 included the distribution of deer in the current year. In the study site, deer abundance halved due to a massive hunting from June 2010-March 2011. Our results suggest that leech abundance is generally affected by deer, but it takes times for leeches to catch up with the rapid changes in the distribution of their hosts.