A power transmission device of the present invention is a power transmission device for a vehicle, including: a generator configured to be driven by power of an internal combustion engine; a travel motor configured to be driven by electric power generated by the generator and to drive a drive wheels; and the drive wheels configured to be driven by the power of the internal combustion engine or power of the travel motor. The power transmission device includes: a first power transmission path configured to transmit power between the travel motor and the drive wheels; and a first clutch mechanism configured to allow or interrupt power transmission through the first power transmission path.