The purpose of this study is to analyze and explain the relations betweentext complexity and tasks in textbooks. In order to conduct thisresearch, we discussed preceding studies regarding text complexity andreadability conducted recently, especially after 2010, and tried to suggesta new direction for researches on text complexity and types of texts intextbooks. We need to classify texts in textbooks such as ‘Introductiontext’, ‘Main text’, ‘Explanation text’ and ‘Task text’ which have not beenpaid attention so far in discussing text complexity. This study also tried toexplain the relations between text complexity and Task text by adaptingand analyzing the same text which were included in Korean textbooks ofmiddle and high school respectively.