Beneficiary principle as one of the principles of administrative and civil proceedings under the set of fundamental principles of correspondence is the right to sue in an independent court and to be heard within a reasonable and conventional deadline. Based on this principle, a person has the right to file a lawsuit if he has an independent, existing, Shariah and legal interest. The rational basis and natural justice can be considered as the basis of the beneficiary principle. The principle of beneficiary in administrative proceedings has a broader meaning than its meaning in civil proceedings. The absence of a beneficiary condition in the petition for the annulment of government approvals and regulations in the Court of Administrative Justice or the possibility of appeal and objection to the decision in the assumption that the judge of appeal or the court of first instance learns of his mistake, and the possibility of filing a complaint in the branches of the Court of Administrative Justice based on "Public Prohibition" and "Public Law" confirm this. Guaranteeing the right to sue also requires the use of the criterion of "rational interest" in administrative proceedings instead of the criterion of existing, direct or actual benefit in civil proceedings. In this article, we apply and explain the principle of beneficiary in administrative and civil proceedings with an analytical and descriptive approach to the theories, laws and jurisprudence.