To improve the fuel economy of a vehicle while preventing a hydraulic torque transmission device from being axially moved.

A torque converter 100 comprises a torque converter body 1, a damper mechanism 8 for elastically connecting the torque converter body 1 to a crankshaft 10 in the rotating direction, and an inertia member 2. The torque converter body 1 comprises a front cover 3, a front boss 34, an impeller 4, a turbine 5, and a lockup mechanism 7. The damper mechanism 8 comprises an input rotary body 81 fixed to the crankshaft 10 and a spline hub 85 fixed to the front boss 34. The inertia member 2 is fixed to the input rotary body 81 of the damper mechanism 7.