Hamaguchi Osachi (1870-1931) is known among other things for his role as the 27th prime minister in the early Showa Era to lead the Minseito (his ruling party) Cabinet. It has been said that he carried out both domestic and foreign policies the most in the prewar party politics. Inoue Junnosuke (1869-1932) served as the minister of finance under the Hamaguchi Cabinet and carried out so called "Inoue financial measures" by practicing a belt tightening fiscal-monetary policy, and by announcing the lifting of an embargo on the export of gold. This paper introduces four letters sent from Prime Minister Hamaguchi to Inoue, the cabinet minister of finance. The four letters are in Inoue Junnosuke Collection owned by Libraries of Graduate Schools for Law and Politics/Faculty of Law Center for Modern Japanese Legal and Political Documents in University of Tokyo.