Surprisingly, although the term reading activity is common in the reading education, there has been little effort to unpack its meaning. This study starts from the needs for the understanding of what is meant to. This study aims to discuss the hierarchy of reading activity, and to identify the problem in reading education based on it. The reading activity has the hierarchy of 'reality', 'practice' and 'method'. The reading activity in reality is refer to that abstracted from a real world. It related to the reading in a course, that is, one of subjects. So, it is examined with the relation to why is taught and what is oriented to. In contrast, the reading activity in practice is related to the pervasive and numerous reading in a real world. This reading concerns the categorization and the selection of learning contents. The reading activity in method supports the activities in practice reading. Related to the issue of 'task', this reading is of great use in reading instruction. It requires to the study of task-design principles for reading classroom. Finally, this study suggests that such problems is individually examined in terms of activity-based reading education.