Purpose: The purpose of this study was to assess the differences of exercise intensities between tennis and boxing game in interaction game-Wii Sports. Methods: Twelve sedentary subjects (24.20±1.48 yrs.) without any experiences of playing Wii sports video game were recruited for the study. All subjects were required to play a 30-mins tennis and boxing game of Wii Sports in random order on separate days. The portable cardiopulmonary analysis system, MetaMax 3B and Polar system, were used to collect the physiological responses, included the VO2, HR, MET and RPE. The paired t test was used to examine the differences between tennis and boxing game. Results: The VO2, HR, MET and RPE of boxing game were significantly higher than tennis game (VO2: 25.40±1.27 vs. 20.70±1.43 ml/kg/min, HR: 164.50±12.03 vs. 136.80±7.88 beats/min, MET: 7.20±0.35 vs. 5.90±0.38, and RPE: 17±1.44 vs. 13±1.72; p＜.05). Conclusion: To sedentary people, tennis game of Wii Sports is the middle level of exercise intensity. However, boxing game reaches to the hard intensity. Therefore, people who is not able to do hard exercise, needs to think over the potential risk in boxing game of Wii Sports.