To lengthen the life of a bush, a bearing, a seal and the like as a high speed rotating part and reduce the noise of a gear by holding down the relative rotating speed of a countershaft, etc., supporting an auxiliary turbine in a four-element and two-stage type torque converter.

This torque converter has a stator 5 supported on a case 3, a pump 7 fixed to an input shaft 6, a main turbine 9 fixed to a turbine shaft 8, and the auxiliary turbine 13 connected to the countershaft 11 associated with the turbine shaft 8 to be rotated in the reverse directions. The auxiliary turbine 13 and the countershaft 11 are secured to each other, and a one-way clutch 19 is provided on the middle of a power composing mechanism 10 associating the countershaft 11 with the turbine shaft 8 to be rotated in the reverse directions.