This article is devoted to the scholarly work of the prominent Russian historian, Doctor of Sciences (History), Professor of St Petersburg State University Mikhail Pavlovich Iroshnikov. A student of two well-known St Petersburg-Leningrad scholars, Alexander Ignatievich Andreev and Sigismund Natanovich Valk, M. P. Iroshnikov became one of the leading specialists in the field of the political history of Russia of the 20th century, the history of state and law, the history of state institutions, archives, source studies, historiography and archeography. The successor to the traditions of the St Petersburg historical school - the school of S. F. Platonov, A. S. Lappo-Danilevsky, A. E. Presnyakov - M. P. Iroshnikov not only became a recognized Russian archaeographer, an expert in archival documents, but also a thoughtful, attentive researcher. The most important academic achievements of M. P. Iroshnikov was the study of the creation, activities and personnel of the Soviet government in 1917-1922, and the discovery and introduction of the census of Soviet employees in 1918 into the scholarship. The article analyzes the work of M. P. Iroshnikov in organizing and implementing many of the largest domestic archeographic projects: the publication of the works of V. N. Tatishchev, decrees of the Soviet government, the Radziwil Chronicle. The article also examines the pedagogical activity of M. P. Iroshnikov in St Petersburg State University, where he continued the traditions of his teachers in educating historians, archeographers and source specialists.