In the field of sports psychology, it is said the presence of cheering spectators has a positive effect on the mental state of athletes. While studies have been conducted to examine the effect of agents as coaches or partners on the motivation of athletes, the effect of cheering from agents has not been studied. In this study, to investigate the effect of cheering by agents, examining the experimental conditions in a preliminary experiment was followed by two surveys which were conducted with the aim of examining the effectiveness of agent cheering on the motivation of the competitors. In the preliminary experiment, we selected suitable timings of the cheering and gestures for agent cheering. In the first survey, we compared the impressions of the agents cheering the competitor in three conditions: “cheering by computer graphics (CG) animation and voice agents,” “cheering by voice agents,” and “no cheering” by Web questionnaires for beginners and experts, respectively. In the second survey, we compared the impressions of the agents cheering for the competitors in two conditions: “cheering by CG animation and voice agents,” and “no cheering” for beginners. From the first survey, it was found that the “cheering by CG animation and voice agents” was effective in motivating the competitors. From the second survey, it was confirmed that “cheering by CG animation and voice agents” increased the motivation and work performance of the competitors.