A power transmission device include: a differential having three rotational elements; and a connection switching device that selectively switches a connection relationship among an input shaft, a first output shaft, a second output shaft, and the three rotational elements. Further, the connection switching device selectively fixes any one rotational element to a fixing member, the second power source is coupled to rotational elements other than the rotational element fixed to the fixing member, the differential can be switched between modes including a first mode where any one rotational element among the three rotational elements is coupled to the input shaft, one of the remaining rotational elements is fixed to the fixing member, and the other is coupled to the first output shaft, and a second mode where the three rotational elements are respectively coupled to the second power source, the first output shaft, and the second output shaft.