3-D models of various types of objects such as a robot body, and a peripheral
equipment, a machine, a part (workpiece), of the robot, are stored in an object
library in advance. Dimension line data of an edge line of which dimension can
be changed, and constraint condition for constraining coordinate positions of apexes
which can be changed are also stored in the object library. A model having the
shape corresponding to the shape of the object to be used is selected from the
object library, and the dimension of the shape is set. The dimension of the selected
model is modified so that the shape of the model corresponds to the shape of the
actual object. Using the model of which dimension was adjusted, animation motion
of the robot is formed on a display screen. With the above arrangement, it is possible
to easily set and change object 3-D models relating to a robot motion.