The invention provides a power transmission device for a vehicle and can reduce noise by suppressing vibration while minimizing increase of a weight of a mission case of a power transmission device for a vehicle.As a mission case (11) is composed of a supporting frame (51) connected to a driving source (E), and a seal cover (52) covering the supporting frame (51) and a plurality of transmission units (14), and the supporting frame (51) is composed of a pair of side frames (54, 55) supporting both end portions of an input shaft (12) and an output shaft (13), and connection frames (56, 57) connecting the pair of side frames (54, 55) at a position free from interference with a moving locus of a connection rod (33) between the input shaft (12) and the output shaft (13), the supporting frame (51) bears a supporting function for supporting the input shaft (12) and the output shaft (13), and the seal cover (52) bears a sealing function for preventing noise from the mission case (11) and leakage of an oil, thus vibration control and noise control of a continuously variable transmission (T) can be achieved while minimizing a weight of the mission case (11).