Background and purpose: The influence of fundamental human rights in different fields of legal knowledge shows that the pure and positivist view of relationship between fundamental human rights and private rights, and in other words, to examine the mechanisms of human rights application based on fundamental rights in the private law system.

Materials and methods: This article is descriptive and analytical. Materials and data are also qualitative and data collection was used in collecting materials and data.

Ethical considerations: In this article, the originality of the texts, honesty and trustworthiness are respected.

Findings: The findings showed that fundamental human rights have played an essential role in the field of private law in the world today, and specifically in the field of contract law; In such a way that the content of the rules of private law, as well as the rules and principles of contract law, should conform to this type of rights. Fundamental human rights have affected private rights as well as private contracts in various direct and indirect ways.

Result: The result is that the application of human rights based on the constitution in private law is a challenge for many legal systems in the world, which exists in relation to all human rights based on the constitution, especially the right to equality. In the analysis, for example, Germany, Italy, Japan, Switzerland, and Spain have been the focus of the research as selected countries.