This paper aims to examine the differential degree of the task difficulty presented in high school English activity books. To achive the aim, the researchers analyzed tasks for three levels(high, intermediate, and low) in five English activity books currently published based on the revised 7th National Curriculum for high school freshmen. The criteria utilized for grading task difficulty are modified from Ellis(2003a, 2003b) which were developed to account for task complexity in terms of input, conditions, processes and outcomes. The results revealed that in general, the tasks of the activity books were organized in the sequential order of difficulty from low, imtermediate to high proficiency, but the difference of task difficulty across the three proficiency levels was not significant. It was also discovered that among three main factors determining task difficulty, task condition, task process, and task outcomes, task process and required task outcomes were more frequently adopted to di fferentiate the task difficulty level. In addition, there was lack of communicative tasks integrating four language skills (listening, speaking, reading, and writing) in all the five activity books. Further study suggesiotns and limitations are followed.