The Holocene population growth and migration rate of Fagus crenataa in southwestern Hokkaido (Yakumo area) was investigated based on pollen analysis. The species invaded a Quercus-dominated forest 3, 400 years BP; subsequently the population grew progressively and was saturated after 1, 700 years. Quercus population decreased rapidly at the initial stage of Fagus crenata invasion, attained stability and then gradually decreased. The intrinsic growth rate (0.0031) of Fagus crenata, fitting the logistic growth model, is in good agreement with the rates known from central and northeastern Honshu. Doubling time is 230 years. The migration rate is extremely low (about 20m/yr) compared with rates in northeastern Honshu, with that of F. sylvatica in Europe, and with that of F. grandifolia in North America. The low migration rate in southwestern Hokkaido implies that the population was established by seed dispersal, whereas the population in northeastern Honshu was established by expansion of extant sparse populations. The long term (1, 700 years) required for forest replacement probably results from strong competition with resistant forest species such as Quecus, etc.