In this study, we experimentally investigated the influence of the amount of dissolved air in working fluid and the rotation speed ratio of turbine to pump elements on cavitation phenomenon in automotive torque converter. In order to directly observe the cavitation phenomenon, transparent model was used. The applied charge pressure was varied to change the significance of cavitation. The pump and turbine torques were simultaneously measured to clarify the relation between torque performance and cavitation phenomenon. As a result, the cavitation region was found to depend on the speed ratio; cavitation occurred on the suction side of turbine blades at low speed ratios while in the pump region at high speed ratios. The effect of the amount of dissolved air was significant, which enhanced the growth of cavitation bubbles through the deposition of dissolved air. In such cases, with the further decrease of charge pressure, a large number of gaseous cavitation bubbles appeared in the whole flow passage. The torque performance was deteriorated at this stage.