人口預期壽命的變化一直以來皆被視為是人類發展與進步的指標之一，其成長更為人們所樂見。當人類預期壽命普遍成長且達一定壽命水準時，兩性存活年數的差距仍為一常見的現象。假設社會的發展與變遷對同一社會中的兩性人口造成相異的衝擊，此種差異性會進一步透過兩者間壽命差距的狀況加以反映時，在追求兩性平等與均衡發展此社會目標之驅動下，對兩性壽命水準差距狀況的瞭解乃為提升兩性存活狀況、創造均衡之兩性社會並進而採取相關策略前重要的一步。 本研究利用內政府統計處所編列之台灣地區簡易生命表做為主要的分析資料，從透過對台灣地區兩性壽命差距於國民政府遷台後之1950起至2004年此55年間變化之關注做為出發點，發現兩性壽命於55年間其增長變化上雖然呈現相似的變動狀態，然而女性於各時期內優於男性之成長幅度則是造成日趨擴大之兩性壽命差距之由來。又兩性出生時平均餘命其變動上所呈現的階段性則與兩性壽命差距水準變化上所出現的四階段有其關聯性。此外，兩性於各年齡別平均餘命之增長，大致來說，主要發生在10-60歲組中，70歲以後之較高年齡組中，兩性存活餘命的成長則較不顯著，且兩性餘命差距隨著年齡別的增加而減少。兩性於各年齡別上餘命之差距，在研究觀察的55年間呈現穩定，只是，1960年以前兩性出生時平均餘命與其他較高年齡組上之平均餘命間呈現較為特殊的型態，此乃說明造成兩性壽命差距之年齡別死亡率有異。 本研究將Arriaga(1984)所提，用以分解兩相異之平均餘命，而以不同年齡別中兩性死亡率差異分別對兩性預期壽命差距所作之貢獻加以表示時，發現，兩性在40-79歲間死亡率的差異是造成兩性壽命差距最主要的貢獻年齡別，其中以60-69歲組為最。此外，面對0-9歲組中兩性死亡率差異狀況對該時期兩性預期壽命差距之貢獻型態於1960年前後所呈現之相異性時，一方面有對該時期兩性死亡率之資料加以檢定之必要性外，其所可能象徵之女性生存狀況受其地位改善之影響，抑或為男性存活狀況變化等推測的驗證雖不在本研究所觸及之範圍內，然而透過本研究分析結果中所掌握造成兩性壽命差距之年齡組別，則有助於日後在企圖釐清造成兩性壽命差距之因以進一步改善兩性存活狀況時一切入點。 / Life Expectancy of human beings, one of the indices of human development, has been generally growing since the beginning of the 20th century and the increase in the life span of human is also taken as the result of the improved medical techniques and social conditions. In the face of the growth in life expectancy at birth both of the male and female populations in Taiwan during the past 55 years, 1950-2004, the gender differential of life expectancy at birth or at any other specific age still exited and even got expanding. The difference in life expectancy at birth between the male and the female was 2.64 years and in the year of 2004, it came to be 6.24 years. Suppose the growth of human life expectancy at birth or at any specific age in both female and male populations implies that social changes and developments brought positive impacts not only on the female but also on the male during the observation period of 55 years. Obviously, the existing and expanding gender differences in life expectancy somewhat indicates that the impact of the social changes and developments on the male and the female weren’t comparable in qualities. The main concern of this article is about the change of the differences in life expectancy at birth between the male and the female in Taiwan during the past 55 years, 1950-2004. Dismissing the discussion and investigation of the practical and real causes of the gender difference in life expectancy, the researcher intended to give the reason to the expanding gender difference in life expectancy by comparing the way male and female life expectancies evolved. In addition, adopting the decomposition method developed by Arriaga(1984) originally for decomposition of changes in expectation of life at birth, the researcher was using this method to decompose the gender differential in life expectancy at birth and evaluated the contribution of the gender differential in mortality within each specific age group to the ultimate differential in life expectancy at birth between the male and the female each year during the observation period and the shifts in the significance of these age groups in the past 55 years. In this article, the researcher separated a person’s life into several age groups,0-9,10-19,20-29,30-39,40-49,50-59,60-69,70-79 and 80 above, to symbolize the different stage of a person’s life. The male and the female experienced similar pattern in the changes of life expectancy. However, the improvement of female life expectancy was greater than that of the male’s in any specific period of the past 55 years , which caused the increasing difference in life expectancy between the male and female in Taiwan. The higher the age is, the less the gender difference in life expectancy at that specific age is. As the male is able to live long enough to a higher age, they are more likely to overcome the survival predominance of the female and the gender difference in life expectancy at a specific age would diminish. In addition, as for the contributions made by each specific age group, during the observation period of 55 years, gender differential life expectancy at birth had been coming from the gender differential in death rates within 40 to 80 years old. The contribution made by the age group of 60-69 made had been the most significant one. Mostly, the living ability of the female was much more superior to that of the male at any specific age even if the significance, each age groups held, somewhat had been shifting during the 55 years. Noticeably, the type of the contribution, age group of 0-9 made, was very different after 1960. Before 1960, men demonstrated a better survival ability than women did within this age group; however, after 1960, the superiority of men came into disappearance. As for the change of the contribution this age group of 0-9 made, we need to have more information and data to gain the further ideas it might bring about.