The theme of this final paper is the lawfulness of public administration decision-making and action. The legality of the work of the administration is one of the fundamental requirements of every modern and democratic state and is a standard that receives considerable attention. The paper deals with the notion of administration which clarifies the definition of administration. Management is a set of state bodies designated by the positive norms as administrative, bodies of the unit of local and regional self-government, whose activity is particularly evident in the direct implementation of the law, the resolution of administrative matters, the implementation of administrative control, the implementation of material activities and other administrative and professional tasks that are in accordance with the requirements of social environment and the principles of the legal system put under jurisdiction. The second chapter deals with the principle of legality in the work of administration as a fundamental principle of the whole legal system, and the historical development of the principle of legality, which emphasizes the French Revolution of 1789, in which the idea of respect for man's natuer and reason was born. In the third part of the paper, public administration is considered as the most important instrument of public administration action is a revised decision. The board of directors decides on the rights, obligations and legal interests of individuals, applying substantive administrative rights to th facts. The administrative matter is decided by a settlement. Namely, the fourth chapter of this paper deals in detail with the application of the Law on General Administrative Procedure and the principles of administrative procedure. Despite legal certainty as a goal of any legal system in general, it is sometimes necessary to eliminate the illegality in the legal system that results from an unlawful decision, which is no longer possible either by filing an appeal or by initiating an administrative dispute, given that the time limits for use have expired remedies. Unlawful acts in administrative proceedings may be corrected by appeal and complaint and by extraordinary legal remedies. In the end the paper deals with the notion of administrative dispute in the Republic of Croatia and the Ombudsman as a plenipotentiary of the Croatian Parliament.