The article analyzes the role of the institute of chaplain during the exercise of the right to freedom of religion and belief by the servicemen. The phenomenon of a dual service subordination of a military chaplain which is within the army and church hierarchy has been researched into. This is the major element of the legal nature of the institute of military chaplain. Religious organizations are deprived of the opportunity to conduct religious events without support of military commanders. The service is organized within the established regime which should be followed by everyone without any exceptions and which does not often leave time for religious activity. Attention has been drawn to the fact that the state should create social and legal prerequisites for religious activities of religious servicemen at all military bases and other units because these people are not deprived of their right to freedom of religion but cannot exercise it without the state’s support. Freedom of religion and belief of servicemen can be ensured only by legalization of the institute of chaplain in other words its full legal implementation and certain legal regulation. With this approach the chaplain is the person who has a legal status and bears responsibility for improper performance of his/her duties. As experience of Ukraine and other states shows, activity of military clergy which aims at ensuring the exercise of the right to freedom of religion by the servicemen is one of organizational measures taken by the state to protect the rights of religious servicemen. As a result, the state has to develop a close cooperation with certain religious organizations to solve tasks during the exercise of the right to freedom of religion by servicemen. The current issues of legal regulation of the chaplain institute in Ukraine have been analyzed. Necessity to adopt the law ‘On Military Chaplain’ has been proved. The main subject of this law should be a legal status of a military chaplain, his/her subordination, training, social, methodological and financial support.