雖然公共投資在經濟中所扮演的角色非常重要，學術界對公共部門投資行爲的理論研究依然十分缺乏。本文爲彌補此項缺陷，特別建立一個簡單的動態模式，並應用最適課稅方法，以檢討公共投資與其他財政變數的最適行爲。假設勞動的供給彈性等於零，並設公共投資與課稅的目的，在於追求某一代表個人效用之最大化，並符合政府預算式之限制，本文仔細討論公共資本存量的長期均衡水準，其社會報酬率，及融通此公共計劃所需課徵之所得稅的最適均衡值。

Despite the important role public investments play in an economy, only a limited amount of theoretical work has been done on the behavior of the public sector as an invest­ing agent. The present paper attempts to fill this gap by formulating a simple dynamic model and then applying the optimal taxation approach to it to investigate the optimal paths of public investment and other fiscal instruments. Assuming labor supply to be in­elastic, this paper examines the steady-state value of public capital stock and its social rate of return and the optimal rate of income tax which is used to finance the investment project.