The purposes of this study are to analyze logging costs of thinning Taiwan fir, and to compare thinning efficiency between operations by contract and by agency. Four Taiwan fir stands in the LiuKuei experiment forest were chosen for thinning and a small quantity of thinned logs were bucked, skidded and transported to Taipei for milling. The average logging cost including felling, bucking. and skidding was NT$11,144/m^3 (~US$405/m^3), which was much higher than imported log prices in the market. Efficiency of thinning operation by contract was found to be higher than that by agency.