A fluid coupling power transmission is constructed such that a pump impel let and a turbine runner are arranged to face each other in a housing, to which torque is inputted, and such that a lockup clutch is disposed in the housing for transmitting the torque from the housing to the turbine runner. The fluid coupling power transmission comprises: a damper mass made rotatable relative to the housing and arranged at the side facing the pump impeller across the turbine runner; an elastic member adapted to be compressed by the revolution of the, damper mass relative to the housing; a lockup piston interposed between the damper mass and the turbine runner and pushed by oil pressure toward the damper mass into selective engagement with the damper mass; a first oil pressure chamber adapted to be fed with the oil pressure for pushing the lockup piston toward the damper mass; a second oil pressure chamber formed between the lockup piston and the damper mass, when the lockup piston engages with the damper mass, and adapted to be fed with oil pressure for separating the lockup piston from the damper mass; and a reaction mechanism for applying a reaction to the damper mass In a direction to separate the damper mass from the housing against the force for the lockup piston to push the damper mass.