AOGCM simulations of the mid-Holocene tend to largely underestimate annual mean temperature over land in northern hemisphere compared to that of paleodata reconstruction. While the vegetation feedback has not been yet quantitatively reported, its neglect is suggested to be one of the cause of this underestimation. Here, we perform several experiments using an atmosphere-ocean-vegetation coupled model and quantify a vegetation-induced feedback in the mid-Holocene climate using MIROC GCM. Our result indicates an annual warming of +1.3K over land north of 40°N in the mid-Holocene, much larger than the previous GCM results. This warming is due to direct amplification of warming over high latitude land through increases in vegetation and reduced albedo during the summer and indirect amplification through sea-ice feedback in autumn and winter and snow albedo feedback in spring. These feedback were not properly represented in previous GCM analysis.