This study was designed to estimate the effect of computer game on responses in the autonomic nervous system in children by using power spectral analysis of heart rate (HR) variability. We used two different games that contained a battled, excited game (S) and a relieved, mild game (M). The results obtained were as follows: 1) HR in S during game tended to be higher than tnat in M. An index of sympathetic nervous system (SNS) during game was higher than during recovery in S, but showed an opposite change in M. Therefore, S might induce stress response during game while M might do it after game. 2) HR during individual mode in S tended to be higher than during mode in playing against other player. 3) HR, SNS and an index of parasympathetic nervous system (PNS) at 10th min. after game were similar to rest-level in both games. 4) There was positive, significant correlation between level of game master and PNS (y=0.091x+4.111, r=0.765, p<0.05). The results suggested that the responses in the autonomic nervous system in children during game were influenced by the type of game and the level of master.