This paper describes the developmental principles of hyper media instructionalmaterials. The studies of hyper media in Japan give instructional environment some useful consequents. But their studies have the same method as CAI. Essentially hyper media instructinal materials differ from CAI. Especially they are distinguisched by Interactivity. Therefore we must study interactivity as such than ever. Current studies of hyper media instructional materials, nevertheless, trend to cognitive psychological approach, and make every effort to develop them. Here are some problmes of the studies of hyper media instructional materials. This study analizes Learner-Computer Interactivity as such, and tries to clear principles of behavior in interaction. Readers will discover the Hypermedia as drama and will explore philosophical, psychological and technological background to creat effective interaction.