Suh, Hyuk · Ryu, Sukyeong The purpose of this study is to analyze and explain the relations between text complexity and tasks in textbooks. In order to conduct this research, we discussed preceding studies regarding text complexity and readability conducted recently, especially after 2010, and tried to suggest a new direction for researches on text complexity and types of texts in textbooks. We need to classify texts in textbooks such as ‘Introduction text’, ‘Main text’, ‘Explanation text’ and ‘Task text’ which have not been paid attention so far in discussing text complexity. This study also tried to explain the relations between text complexity and Task text by adapting and analyzing the same text which were included in Korean textbooks of middle and high school respectively.