This study was designed to compare the influences of walking, resistance exercise, and badminton, a game involving physical activity, on mood and heart rate variability (HRV). Forty-eight healthy young adults (23 women) performed submaximal strength tests and an incremental treadmill running test to determine peak oxygen consumption (VO₂peak). On subsequent days, 4 counterbalanced interventions were done: 10 min of either walking, resistance exercise, badminton, or seated rest (control condition). Mood and HRV were measured before and after each intervention. As indices of mood, Pleasure and Arousal levels were measured using the Twodimensional Mood Scale. Power in the high-frequency range (HF) and the ratio of power in the low-frequency range (LF) and HF (LF/HF) were calculated as indices of HRV. Oxygen consumption (VO₂) was monitored during each intervention. The influences of physical activity types on mood and HRV were analyzed by two-way repeated ANOVA using a Mixed model. Then, individual differences in mood change and HRV were estimated by intra-class correlation coefficients (ICC) calculated from the outputs of the Mixed model. The exercise intensities of the interventions were 45.2%VO₂peak for walking, 41.3%VO₂peak for resistance exercise, 74.3%VO₂peak for badminton, and 9.9%VO₂peak for seated rest. The results of ANOVA revealed that badminton increased the Pleasure level significantly in comparison with resistance exercise and seated rest (p ≤ .044). All exercise interventions significantly increased the Arousal level in comparison with seated rest (p < .001). For HRV, HF after badminton and resistance exercise was significantly lower than after seated rest; LF/HF after badminton and resistance exercise was significantly greater than after seated rest. No difference in HRV was found between brisk walking and seated rest. Although no individual differences (ICC ≤ 0.12) in HRV change were found, individual differences in mood change were evident. Individual differences in changes in the Pleasure level were especially large (ICC = 0.32) relative to those in changes in the Arousal level (ICC = 0.18). These results demonstrate that the effect of physical activity in the form of a game on pleasure mood is greater than for walking and resistance exercise, that physical activity of any type increases the arousal level, and that there are individual differences in the mood changes resulting from physical activity. However, no individual differences were found for HRV change, which tended to be influenced by the type of physical activity. Resistance exercise reduces parasympathetic nervous activity and activates the sympathetic nervous system to a greater degree than aerobic exercise.