本文利用隨機成本邊界函數估算戰後日本（1965-2000年）農家之經濟效率、技術效率和配置效率，並探討農業專業化、作物結構、農場規模、資本集約度等因素對農家經濟效率之影響。實證結果顯示：農業專業化、稻作比例、畜產比例、和資本集約度均對日本農家的配置效率和經濟效率有正面的影響。和1960年代相比，1970、1980年代的日本農家配置效率和經濟效率有遞增的趨勢，但此趨勢在1990年代以後便不顯著；而技術效率在研究期間則沒有明顯的時間趨勢。同時實證結果亦顯示，在農業生產技術日臻成熟的戰後日本，農家經濟無效率主要來自配置無效率，因此，專業農家的養成、資本集約作物的生產、經營耕地面積的擴大等是改善日後農家經濟效率的重要因素。

The paper uses an approach of stochastic cost frontier to analyze the economic, technical, and allocative efficiencies of Japan farm families across the post-war period, 1965-2000. Moreover, the influences of specialization, crop structure, farm sizes, and capital intensity on farms' economic efficiency were also studied. The empirical results show that increases in degree of agricultural specialization, ratio of income from rice, ratio of income from livestock, and capital intensity all were able to improve farms' allocative and economic efficiencies. Compared with the levels in the 1960s, the indexes of allocative and economic efficiencies of Japan farm families were increasing in the 1970s and 1980s and the increasing trend became insignificant after the 1990s. However, the technical efficiency index did not have a clear tendency in the period of study. Moreover, it was also found that the mainly part of economic inefficiency in the post-war Japan came from the allocative inefficiency, although the nation had a matured agricultural production technology. Therefore, cultivation of specialized farmers, production of capital-intensive crops, and enlargement of farming sizes are important for the economic efficiency improvement of future Japan agriculture.