國際關係學者認為一國力量的強弱決定它在國際上的地位。實力強的國家可以依照本身的意志行事，他們會運用有形或無形的力量排除他國的干預與影響，並且能夠順利達成自己既定的外交目標。因此，本文定義國家實力的實質內涵為權力與勢力。然而，衡量一個國家實力的標準有哪些呢?大致上可以分成四個要素:地理環境；人口資源；經濟資源；軍事資源。這四個要素的重要性會隨著時代演進而互有高低，但是基本上還是要從整體的角度來衡量一國的力量，否則會偏重某個要素而產生誤判的情形，所以本文將就這四個要素做更進一步的探討，另外也討論國家實力的近貌，藉此瞭解國家在國際社會運作的實際情形，並且找出合理的衡量標準來評斷國家力量的強弱。

　　　　　Scholars of international relations believe that the strength of a state's capacity decides its international status. States with significant strength can accomplish tasks based on their will. To successfully accomplish their diplomatic objectives, these nations use both tangible and intangible power to prevent other states' intrusion and influence. Hence, the basic concept of a nation's capacity includes power and influence. However, what is the criterion used in measuring a state's capacity? Basically, there are four factors: geographical environment, population, economics, and arms. The importance of these four factors fluctuate over time. But, basically, we need to measure the capacity of a state in its entirety. Otherwise, misjudgment is likely to occur if we overlook any of these four factors. The following report analyzes the four factors in depth to understand the actual scenario of how a state runs on the international stage and discusses the most recent definition of national capacity. We also locate a reasonable criterion to evaluate the strength of a state's capacity.