本論文主要討論跨國廠商為獲取利潤，將考慮到本國進行外人直接投資(foreign direct investment, FDI)，在跨國廠商固定設廠成本明顯很小或很大、本國與跨國廠商生產效率相等或不相等、跨國廠商有或無具備技術外溢效果的情況下，跨國廠商進入本國 FDI ，與本國廠商從事 Cournot數量競爭，本國政府應採取課稅或是補貼之投資政策，才能提高本國社會福利。 本論文發現當跨國廠商的固定設廠成本明顯很小時，必會到本國FDI，本國政府為促進社會福利極大化，無論跨國廠商是否有技術外溢效果皆應該對其採取課稅之投資政策，且為定額之從量生產稅。一旦跨國廠商的固定設廠成本明顯變大時，需在利潤為正值的情況下才會選擇到本國 FDI 。當跨國廠商成本下降或技術外溢效果提高等兩種情況下，均會提高社會福利水準。如跨國廠商利潤為正值，會選擇到本國市場設廠生產，本國政府仍應課稅；但若固定設廠成本明顯增大，跨國廠商發現無利潤，可能不會進入本國FDI，此時本國政府衡量社會福利只要比較本國廠商獨占時為大，甚至可能採取補貼之投資政策，藉以吸引跨國廠商進入本國直接投資，極大化本國社會福利。 ;This thesis discusses the consideration of foreign direct investment (FDI) in a host country by a multi-national manufacturer when seeking profits. When a multi-national manufacturer directly invests in a host country and engages in Cournot competition with host country manufacturers, the host country government should employ investment policies such as either imposing taxes or providing subsidies to enhance social benefits dependent on various factors. These factors include: whether a multi-national manufacturer’s fixed factory setup costs are significantly smaller or greater, whether the host country manufacturer and multi-national manufacturer have equivalent or non-equivalent productivity, and whether the multi-national manufacturer has technological spillover. This thesis found when fixed factory setup costs of multi-national manufacturers are significantly smaller, they will directly invest in the host country. In order to maximize social benefits, the host country government should impose unit taxes on the multi-national manufacturer, regardless if technology spillover has occurred. If the multi-national manufacturer’s fixed factory setup costs increase significantly, it will only choose FDI in the host country if the profits are positive. If the multi-national manufacturer’s costs decrease or technological spillover expands, both scenarios will enhance social benefits. If the multi-national manufacturer’s profits are positive, it will choose to set up a factory for production in the host country market.But if fixed factory setup costs increase and the multi-national manufacturer discovers there is no profit, it might decide not to directly invest. At this time, the government can decide to provide subsidies if social welfare gained outweigh factory setup by a local manufacturer. This will provide incentives for a multi-national manufacturer to directly invest in a host country and maximize the social welfare.
