The author presents the state of research on the legislation of the II RP. Presentation of the representatives of the science of law includes, apart from the period of the II RP, the times of the communist regime and the present. The author emphasizes the high level of regulation of the II RP, despite objective difficulties stemming from historical events. The article stated and justified also directions and research methods of legislation of the II RP. The author presents the view of the need for further studies on the history of the Polish state and law in the years 1918–1939.