國際法植基於自然法。自然可分為兩大部門：原始自然法與派生自然法。原始自然法是由人性中判斷出來，派生自然法則是針對具體狀況由原始自然法判斷出來的。國際法的任務在於落實自然法。國際法應收納自然法原則並予以進一步的開展。國際法拘束力原因、強行法的性質及一般法律原則的性質，可以從自然法角度予以說明。

International law has its foundation in natural law. Natural law can be divided into two categories: preliminary natural law and secondary natural law. Preliminary natural law is derived from the human nature, while secondary natural law is obtained from preliminary natural law in view of the concrete situations. It is the function of international law to implement natural law. International law incorporates the principles of natural law into it and draws the consequences from them. It is possible to obtain from natural law the proper arguments to explain the validity of international law, the essence of jus cogens and the essence of the general principles of International Law.