To prevent knocking noise from occurring resulting from a gear for driving an oil pump installed in a torque converter body.

In the torque converter with a transmission, in which an oil pump 15 for supplying oil selectively into a plurality of clutches of a transmission via selection valves 31 to 34 and a driven gear secured to the rotational shaft are meshed with a drive gear, secured integrally to the rotational shaft with a pump impeller of the torque converter body 1, a check valve 29 is provided in a hydraulic circuit between a discharge side of the oil pump 15 and the selection valves 31 to 34 for temporarily shutting-off of the hydraulic circuit, when the hydraulic pressure on the downstream side will not exceed a certain pressure.