Disclosed is a power transmitting device capable of streamlined structure and control, as well as alleviating energy loss. The device comprises a planetary gear device (30) wherein motive power of an engine (211) and a motor (60) is inputted from a first element and a second element; and a first clutch (10) that transmits, in an interruptible manner, motive power from a second shaft (4) that is linked to the second element, to a first shaft (3) that is linked to a third element and an input shaft (2), while interrupting motive power from the first shaft (3) or the input shaft (2) to the second shaft (4). It is thus possible to start the engine (211) with the motive power of the motor (60), and to drive a vehicle with the motive power of the engine (211) and the motor (60), via the first clutch (10). It is possible to switch motive power of the engine (211) and the motor (60) with motive power transmission switching by the first clutch (10), thus allowing streamlining of structure and control. It is further possible to eliminate a wet-type multi-plate clutch, thus allowing alleviating energy loss.