Movement of the human is achieved by coordinated movements of several muscles. In this paper, measuring the EMG during exercise. After that, we did wavelet coherence analysis. Thereby, we can presume which coordinative relationship between multiple muscles is important. We also have experimented with the same exercise under unstable conditions to investigate the effect of disturbance. As a result of the analysis, correlation is increasing in frequency region of 10 similar to 70 Hz. In addition, I compared the three groups (biceps and biceps, biceps and triceps, triceps and triceps). As a result of the comparison, biceps and triceps group showed highest correlation. At the end, I compared the stable condition and unstable condition. As a result of the comparison, there is a tendency of stable condition showed higher correlation than instability condition. Conclusion of this study is that; (1) coordinated movement between agonist muscle and antagonist muscle is important. (2) there is a tendency of stable condition showed higher correlation than instability condition.