The main purpose of this paper is to illustrate the characteristics of ontology-based authoring tools for Computer Based Training (CBT) systems. It has two major advantages as follows. (A) It provides human-friendly primitives in terms of which users can easily describe their own model of a criptiveness, readability). (B) It can simulate the abstract behavior of the model in terms of conceptual level primitives (conceptual level operationality). In this paper, we will discuss the basic issues on the concept of task ontology and then describe the design principle of an ontology-based authoring tool for Computer Based Training (CBT) systems. Content Areas: computer-aided education Tracking Number: A630 This paper has not already been accepted by and is not currently under review for a journal or another conference, nor will it e submitted for such during IJCAI's review period.