When balls are tumbling down a slanted board on which many nails are attached, the type of bouncing and tumbling are different depending on the coefficient of restitution and the weight of the balls. This study examined if these properties of balls affect the impression of animacy when being viewed. Seven point-light-display animations which were made of video clips of seven tumbling balls and seven stimuli made by playing the same animations in reverse were presented to fifty-nine participants, and they were asked to rate the animacy of each stimulus animation. The results showed that the lower the coefficient of restitution, the higher the rate of animacy reported, and that the heavier the balls, the stronger the impression of animacy reported. It was also clarified that the weight of balls was closely related to the number of bounces in a single point-lightdisplay, i.e. the heavier those balls were, the lesser the number of bounces . These results were discussed from the point of view proposed by Premack & Premack (1995), of "self propelled motion" and " goal directed motion" which are important factors for understanding the perceived intention of moving objects.