本文以民主規模-獨裁規模的差 (Democracy) 做為衡量民主化程度的指標，以吉尼 (Gini) 係數的成長率作為衡量所得不均的指標，以所得水準為門檻變數。結果發現在低所得的國家，民主化程度與所得不均間存在負向且顯著的關係，說明在低所得的國家中民主化程度上升是可以減緩所得不均；而在中高所得國家與高所得國家，民主化程度與所得不均間存在正向且顯著的關係，說明在中高所得國家與高所得國家民主化程度提高反而會使所得不均的情況更為惡化。 This paper tries to investigate the threshold effects of democracy on income inequality. Specifically, we use Hansen’s (2000) threshold regression model to examine the democracy- inequality links varies with the degree of country’s income level. By applying the model to 95 countries during the period 1981-2013, we find that there indeed exists an income threshold in the democracy- inequality link. The empirical results show that low-income countries have a negative and significant relationship between the democracy and income inequality. However, the relation is positive and significant in the middle-income countries and high-income countries. It indicates that the increasing in the degree of democratization would reduce income inequality in low-income countries, but increase income inequality in the middle-income countries and high-income countries.