The paper offers a solution to the scientific problem in the field of science of public management and administration – the substantiation of directions of the development of institutional system of the public social security administration of Ukrainian regions. The present-day institutional system of the public social security administration of Ukrainian regions in the context of its main organizational and functional components were analyzed. With the help of content analysis of the legal base of implementation of these mechanisms of public administration, the scientific approaches to assessment of their effectiveness (typical, methodical, technological) were presented. Using these approaches, it was possible to reveal the range of disadvantages of fundamental laws and regulations in this field. In this regard, the functionality and approaches to the assessment of institutional system of the public social security administration of Ukrainian regions were improved.