本文與既有文獻不同之處，在於本文乃延伸隨機新開放總體經濟模型之架構，並將貨 幣以現金付現法方式融入模型中，研究保護性關稅對開放總體經濟變數的影響。我們得到 隨機性關稅的提高會造成工資水準下降、國內商品價格攀升、消費減少、貿易條件惡化以 及匯率下降的結論，且由於隨機性關稅深化了各國間貿易的障礙，因此一國的福利水準會 降低。與Fender and Yip (2000) 的結論相比，本文發現隨機性關稅增加了經濟體系中的不 確定性因素，因而造成消費的波動程度提高，導致福利水準下降。最後，本文也就關稅政 策協調的福利效果進行分析。

Different from past related literature, this research extends stochastic new open economy macroeconomics model with a cash-in-advance restriction to study the effects of protective tariff. In this paper, we show that the increase in stochastic tariff will reduce wage level, and decrease in consumption due to higher domestic price, price inflation worsens the terms of trade and cause the exchange rate to fall. Moreover, an increase in stochastic tariff will make the trade barriers deepen, and decrease in welfare. To compare our findings with the study of Fender and Yip (2000), we found that the stochastic tariff may increase economic uncertainty, as well as increase in consumption variability, lead to a decline in the welfare. Finally, the welfare effect of tariff policy coordination is also considered.