In this paper, we present a trajectory generation method for companion robot "SELF" with which humans do not get bored. A red ball and a blue ball are displayed on the computer. A human moves the red ball with a track point and a PC moves the blue ball. In using this model, the impressions that the robot behaviors give to the human are examined. We analyze the behaviors of human and generate four basic actions by using spline curve. Combining these actions, the behaviors of the blue ball are generated. The impressions that various robot behaviors give to the human are analyzed through Semantic Differential method.