社會安全制度，以社會保險及公共救助為主體，兩者之中尤以社會保險為骨幹，社會保險通常扮演著重要的角色。當中一項重要的功能即為所得（財富）重分配功能，亦即政府借助社會保險之力，達成安定經濟社會與改善國民所得分配不均，以達公平之目標。 本文在實證方法上採用「吉尼係數法」與「變異係數法」來計算社會保險的所得重分配效果。利用民國八十五年至民國九十一年行政院主計處「中華民國臺灣地區家庭收支調查報告」之調查資料，探討臺灣地區所得分配不均度上升的原因是否來自於城鄉差異，其次是社會保險政策對於平衡城鄉差距是否有助益。 為了衡量社會保險的所得重分配效果是否會因城鄉發展程度之不同而有所差異，將臺灣地區內之城市分為都市、城鎮及鄉村三級，其分層標準係依照行政院主計處「中華民國臺灣地區家庭收支調查報告」之標準分類。本研究以城鄉別與社會保險為研究主軸，探討臺灣社會保險的所得重分配效果是否在不同城鄉間會有所影響。 綜合研究結果及分析，對於民國八十五至九十一年社會保險實施的所得重分配效果所得到的結論為：1.臺灣地區自民國八十五年後無論是區分層級或整體所得分配效果上的吉尼係數均有逐漸縮小的趨勢，代表政府對於平均所得分配之努力是有所成效的。2.在吉尼係數法下，除了「都市層」外，社會保險實施後「城鎮層」、「鄉村層」與整體所得分配效果的吉尼係數值均高於較社會保險實施前，顯示社會保險政策在平衡城鄉所得差異上的力量似乎薄弱了些。3.在變異係數法下，無論是分層效果或是整體效果實施社會保險後整體的所得分配平均化力量均減弱，故社會保險政策在平均所得分配的效果上似乎沒有達到預期的成效。4.綜合上述兩種方法，除了吉尼係數法下的「都市層」有達成社會保險的所得重分配效果外，吉尼係數法與變異係數法的其他層級和整體效果分析均顯示出實施社會保險未達成所得重分配的效果。 / Social insurance and public rescue are two main components of social security system. Especially, social insurance is also the skeleton of social security system, which has many important functions, one of which is improving the inequity of people’s income assignment. It means that the government redistributes people’s income through social insurance to achieve the goal of equity and further to stabilize economic society. This article uses the data of "Republic of China Taiwan area family budget survey reported", which comes from 1996 to 2002 Directorate－General of Budget, Accounting and Statistics, Executive Yuan, R.O.C.(Taiwan), as investigation material. We calculate the income redistribution effect of social insurance by means of "Gini Coefficient method" and "Coefficient of Variation method". This article has two issues, one of which discusses whether the income inequality in Taiwan does come from the difference between city and countryside. The other one is the benefit of social security policy to balance of disparity of city and countryside. In order to assess whether the income redistribution effects of social security has the difference between cities, we divide the cities in Taiwan into three groups: metropolis, countries and villages, according to standard classification of the investigation material. We use difference between cities and social insurance as two axes of our study to evaluate the effect of income redistribution between different cities. To the effect of social insurance on income redistribution from 1996 to 2002, our study has following findings. First, regardless of classification or summation analysis, the Gini coefficient of income redistribution was gradually reducing from 1996 to 2002. This means that income redistribution policy of government is effective. Second, in Gini Coefficient method, country group and village group had higher Gini Coefficient than before executing social insurance policy. The conclusion shows the influence of social insurance was still not efficient. Third, in Coefficient of Variation method, classification and summation analysis both revealed income redistribution was weaker than before executing social insurance policy, so the policy did not achieve the expected effect. From the above findings, although the metropolis group in Coefficient method did improve income redistribution, other analysis did not achieve the goal of income redistribution.