To provide a power transmission device having less power loss and improved vehicle mountability.

The power transmission device transmits power distributed from an input member 4 to a plurality of driven members 1, 2. Herein, pressure fluid is discharged with the relative rotation of a first input element 9R stored in a casing 9C and its discharge amount is variable. A first differential part including a first actuator which can function as a variable displacement pump 9 where torque corresponding to the discharge amount appears on the first output element 9R is arranged between the input member 4 and any one of the driven members 2. A second output element 8R is stored in the casing 9C or another casing 8C in a relatively rotatable manner. A second differential part including a second actuator which can function as a variable displacement motor 8 where torque corresponding to supplied pressure fluid is applied to the second output element 8R and output is arranged between the input member 4 and any one of the driven members 1.