This study is an attempt to present a model of the organization structure for public libraries based on Standards for Public Libraries in Korea. The result of this study is as follows : (1) A library serving $50,000{sim}80,000$ population should be organized with a staff of 4 persons and a part-time typist without actual departments. (2) A library serving $100,000{sim}150,000$ population should be organized with a staff of 10 persons without actual departments. (3) A library serving $400,000{sim}500,000$ population should be organized with a staff of 33 persons. $4{sim}5$ sections and 2 branch libraries leveled with a section. (4) A library serving $900,000{sim}1,000,000$ population should be organized with a staff of $62{sim}66$ persons, an associate librarian, $4{sim}5$ departments, $9{sim}10$ sections and $4{sim}5$ branch libraries leveled with a section. (5) A library serving $1,400,000{sim}1,500,000$ population should be organized with a staff of 95 persons, an associate librarian, $5{sim}6$ departments, $13{sim}16$ sections, $6{sim}8$ branch libraries leveled with a section and a full-time person taking charge of publicity. (6) A library serving $1,900,000{sim}2,000,000$ population should be organized with a staff of 124 persons, 2 associate librarians, $7{sim}8$ departments, 14 sections, 4 separate rooms without actual departments and $9{sim}11$ branch libraries leveled with a section.