We proposed the calculation method of the ventilation threshold using the noncontact respirometry under pedal stroke motion. By the simultaneous measurement with the expiration gas analyzer, we examined the effectiveness of the proposal method. There was high correlation over 0.8 between ventilation variations calculated by our proposed method and the expiration gas analyzer. On the other hand, the correlation between ventilation thresholds calculated by our proposed method and the expiration gas analyzer is 0.735. In this experiment, the sufficient examination seemed to be difficult on the correlation, since the difference between the systemic aerobic capacities of the examinees is small.