The description of enterprise activities is the basis for process improvement and the building of information systems. To describe such activities, it is necessary to model all enterprise activities from an abstract level to a system building level in a stepwise and integrated manner. Many of the existing methods are limited in their ability to do this. To cope with these problems, this study proposes the hierarchical frame of enterprise activity modeling (HF-EAM) which is composed of five modeling levels from an abstract level to a system building level: function level, process level, task level, document workflow level, and event flow level. At each level, activity's semantics, characteristic, relation, and schema are clearly defined. The rules for stepwise and integrated activity modeling are then exemplified with the industrial application of the HF-EAM. In addition, comparisons with other modeling methods are made in order to deliberate the pros and cons of the HF-EAM.