Adult population sizes of ground beetles (Carabidae) in a forest and vegetable field in Nagano Prefecture, Japan were estimated using the removal method. Removal collections using 15 pitfall traps with a lactic acid beverage were conducted at 40-m² survey sites enclosed by a thick plastic sheet for 10 days in September 2002 in the forest site and October 2003 in the field site. Dominant species were Synuchus cycloderus, Pterostichus subovatus and S. nitidus in the forest, and Harpalus griseus, H. sinicus and Amara simplicidens in the field. Population sizes within the 40-m² sites and the density (/m²) of total carabid beetles and dominant species were estimated by the regression and maximum likelihood methods. A total of 250 and 176 carabid beetles were caught in the forest and field sites, and estimates by the regression method were 254 and 180 individuals, respectively. Estimates of dominant species and total carabid beetles by the maximum likelihood method were almost equal to those obtained by the regression method. The observed numbers caught from 10 trappings were almost the same as the estimated values. The correlation coefficients between the number of individuals captured during the ith trapping and the total number captured prior to the ith trapping were less than -0.9, and the precision level of the estimations was less than 0.12. The prerequisite for the removal method and appropriate number of trappings required for estimating carabid population size were discussed in relation to the precision level of the estimations.