The purpose of this paper is to develop a 3-dimensional human model, an ergonomic CAD (Computer-Aided Design) system which would be very helphul in ergonomic design. An interactive program was developed, in which a user could change layout, body size, skin volume, and posture of the human model. As an example, effect of inclination of a steering wheel on visibility of a display panel was demonstrated. he result showed that ergonomic design can be aided by the 3-dimensional human model, and by the perspective graph by which design and evaluation process can be carried out more effectively.