國防預算之多寡直接影響到國防戰力之強弱，然而究竟「多少才夠？」，卻一直是規劃國防預算規模的未決難題。本文目的即為利用內生經濟成長理論來說明我國國防支出規模之適足性問題，以1956年至1998年時間數列為樣本析期間，並使用Johansen的共整合方法進行實證分析。實證結果顯示：每人所得成長率與國防出規模均為I(1)的時間數列，且存在長期穩定均衡的正相關，意指我國國防支出未達最適規模，且增加國防支出規模將有助於經濟成長。

The national security depends on defense spending scale. However, “How much is enough?” has been an open question. In this paper, we use endogenous-growth models and Johansens cointegration analysis to examines the adequacy of defense spending scale in Taiwan from 1956 to 1998. The results of unit root test and cointegration test suggest that both per capita growth rate and defense spending scale are I(1) time series, and have positive relationship of long-run equilibrium. These results imply increasing defense-spending scale promotes economic growth.