The purpose of this paper is to demonstrate disparity factors in income by examining the influence of farm size and farm efficiency on farming income. The following were the four main findings; 1) The influence of farm size and farm efficiency on income showed annual fluctuations. 2) For some cases of large-scale upland farming operations there were large fluctuations in incomes because of fluctuations in farm efficiency, resulting in small average annual incomes. 3) The statistical relationship between revenue and income per unit area was very low, while there was a clear relationship between expenses and incomes per unit area for large-scale upland farming operations. 4) In large-scale upland farming operations where there were decreases in income, financial outlays were still necessary to maintain revenue. As above, large-scale upland farming suffering from lowered incomes showed low efficiency because of increases in expenses to ensure maintenance of revenue per unit area and avoiding overcropping of wheat. These farming enterprises caused some of the problems detailed in literature reviews, and other problems they encounter are to maintain farm efficiency by considering the balance between revenue and expenses.