Overabundant deer populations often cause habitat degradation, for example disappearance of seedling and sapling in forests or soil erosion. Few studies have reported the response of vegetation to deer foraging pressure when deer density decreases; on the other hand many studies have indicated the changes of vegetation when deer density increases. Sika deer Cervus nippon population has irrupted during the 1980s and 1990s in eastern Hokkaido, northern Japan, and causes severe damage to forest vegetation. Thereafter the population has decreased by artificial control by the Hokkaido Prefectural Government based on a management plan. The estimated deer density in Akan National Park (ANP) was 27.1 ± 10.7 deer km-2 in 1993, and significantly decreased to 9.5 ± 2.5 deer km-2 in 2009. Our objective in this study is to identify the response of forest vegetation to the variation of deer density. We established seven sets of an exclosure sites and a control site in 1995 in ANP and have sampled by the quadrat method from 1995 to 2011. We analyzed the 15 palatable herb species and 2 unpalatable species, and found the cover and maximum height of Sasa senanensis and Trillium spp. on the former increased and Senecio cannabifolius on the latter decreased in the control sites. We also determined the impact of the deer fence and relative photon density on the seedling and sapling’s density and survival. We suggested that herbaceous plants were recovering because of reduction of deer density, but it was still high for survival of seedlings and saplings.