This study aims to clarify the formal characteristics of back-of-the-book indexes appended to textbooks for librarian training courses. To achieve this, 220 textbooks published in Japan between 1950 and 2025 were examined and their contents analyzed. The results showed that 179 textbooks (81.4%) included an index. Similar to general books, most textbooks employed typographical devices such as indentation and line breaks for index headings, ensuring readability. In terms of layout, smaller type sizes than those used in the main text and multi-column formats were commonly adopted to accommodate a larger number of index terms. Although subheadings and ‘see’ references were used more frequently than in books on other subjects, the use of cross-references was still insufficient and cannot be regarded as fully widespread.