Abstract: Current advances in information technology have led to increased interest in digital textbooks delivering digitally enhanced content. As more functions are integrated into the digital textbook platform with advances in digital technology, its use becomes complex and various usability problems arise in the user interface. Many researchers have defined usability according to measurable attributes. Usability attributes are important because usability design principles can be inferred from them. However, few studies have examined the usability attributes for the digital textbook platform. Thus, the purpose of this study is to explore factors that are critical to the attributes of usability for digital textbook