According to research on the effects of posture on psychological states, high-power poses—with the body spread wide open—lead to high-arousal positive emotions, whereas low-power poses—with the body slumped and constricted—lead to low-arousal negative emotions. However, postures that lead to both high-arousal negative and low-arousal positive emotions have not been investigated yet. Although relative comparisons between postures have been made, the positioning of postures on the two-dimensional coordinates created by arousal and valence has not been clarified. Therefore, the purpose of this study was to explore and clarify which postures lead to the four types of emotions: high-arousal negative, high-arousal positive, low-arousal negative, and low-arousal positive. In Experiment 1, 29 participants (13 men and 16 women) adopted 12 sitting postures for 1 minute each. In Experiment 2, 25 participants (13 men and 12 women) adopted six sitting and six standing postures for 1 minute each. Arousal and valence were measured after each posture, and heart rate was measured during posture maintenance. Arousal and valence after adopting the postures were compared with the neutral arousal and valence. As a result, postures leading to high-arousal negative and low-arousal positive emotions were identified. In addition, postures leading to high-arousal positive emotions, which are the high-power poses, were identified. There were no differences in the magnitude of psychological effects between sitting and standing postures.