Farm management scale is an important factor which influences farming income that is an essential source of income for a full-time farm family to cope with his living expenses. In Taiwan, however, the management scale of farming has become trifling and farming itself subsidiary. Therefore, the direction of agricultural management must be directed towards assisting and guiding full-time farm families to establish the minimum farm management scale in accordance with their various crops and management types. And, in order to enable the three factors---Product value, farm management expenses and home consumptive expenditure---to get balanced off, a farmer ought to have the minimum area under his cultivation (in this study it is called the minimum scale of full-time farm family). In this article, a full-time Taiwanese rice farm family of book-keeping nucleus farms is the object of study. Investigation and analyzation of the results done, it is concluded that 4.4 hectare is the rice farming area that enables a full-time farm family to earn an income from his farming to balance off his home consumptive expenditure though those who have this scale (including area more than this) of farming land occupy only 7.0% of all the farm families in Taiwan. Henceforth, therefore, the grovernment should first provide them with necessary assistance, including funds and training for management ability, thus making them the service centers to offer farm management service to the farms around them when they are ready. It is held that the problem of farming management in Taiwan could only be solved through this practicable approach.