本文於R&D 內生成長模型內鍵入連續的不完全競爭市場結構， 討論中間財廠商與最終財廠商之間的互動，以及政府實施補貼政策 或課稅政策對經濟成長的影響。我們發現中間財廠商與最終財廠商 向前垂直整合或向後垂直整合的總和利潤大小，決定於中間財與最 終財的廠商數目大小。在廠商向前垂直整合的例子中，若最終財市 場的競爭程度較低，則市場經濟下產生的R&D 較少，以致於存在較 低的平衡成長率，因此政府應實行補貼R&D 政策以提升經濟成長率； 反之，若最終財市場為完全競爭，則R&D 生產過多，因此政府應實 行課稅政策以讓平衡成長率接近社會最適成長率。在福利水準方面， 若政府採行最適補貼（或課稅）政策，將使得競爭均衡的福利水準 等於社會最適的福利水準。

To explore the performance of R&D along the growth path of an economy, this paper considers a vertically connected imperfectly competitive market structure in the context of an endogenous growth model, where the intermediate goods firms and final goods firms interact with each other and the government implements a subsidy/tax policy. Our findings show that the amount of aggregate profits generated after forward or backward integration is based on the number of intermediate goods firms in relation to the number of final goods firms. In addition, when the firms engage in forward integration, the R&D activities will lead to ambiguous results according to the degree of competition in the final goods markets. If the final goods market is more imperfectly competitive, there will be too little R&D activity at the market equilibrium. Since the market equilibrium economic growth rate is lower than the socially optimal economic growth rate, the government should implement a subsidy policy so as to increase economic growth. On the other hand, if the final goods market is perfectly competitive, then there is too much R&D activity, and the government should implement a tax policy to boost economic growth. Lastly, the government can enforce the optimal subsidy/tax rate to increase the welfare of balanced growth equilibrium to the level of social optimum.