The purpose of this study integrates the study “Study about manufacturing learning support system " and the study “Study about 3D-CAD education system" on which we have worked and also developed CAM/NC education system. And this study establishes a class system of practicing manufacturing education using a CAD /CAM system. Therefore, we made the system which integrated on-line, and used the system. But, new trouble has formed at the stage of this practical use. This report describes this trouble and countermeasure.