The aim of this paper is to present the most important activities of the National Public Prosecutor’s Office of the Republic of Poland in cases concerning operation of the Ministry of Justice, one of the many agendas of the legal practice of the National Public Prosecutor’s Office of the Republic of Poland, a centralised state organ of legal representation of material and public interests of the Polish state in the period of the Second Polish Republic. The legal practice of the National Public Prosecutor’s Office covered legal representation before private law or public law courts and in proceedings carried out by administration authorities, issuing legal opinions on request of public authorities or other authorised entities, and collaboration in executing agreements in material matters of the state or of entities entrusted by virtue of the law to the legal care of the Office. In cases concerning the Ministry of Justice, the National Public Prosecutor’s Office undertook all types of office-related activities. This study presents an analysis of yearly reports of the President of the National Public Prosecutor’s Office, jurisprudence and rulings from courts and tribunals issued on the initiative of the Office. The research results demonstrate that the activity of the Office contributed to protection of material and public law interests in Poland reborn after the period of partitions in the context of operation of the Ministry of Justice.