The utility model provides a seat air conditioning device of a vehicle. According to the seat air conditioning device of the vehicle, a film part (36) arranged all over the back side (26) of a cushion extensively in a jointed mode is flexible, so that the film part (36) can deform easily along with the curving of the cushion (16), and therefore a ventilating channel (46) can be formed in the back side (26) of the cushion (16) to prevent the riding feel from being worsened by the film part (36). Furthermore, due to the fact that one end (38b) of an air duct (38) is harder than the film part (36) and the tubular portion (38c) of the duct, the film part (36) and the tubular portion (38c) of the duct can still deform along with the curving of the cushion (16) even if the cushion (16) is curved after people sit on the seat, and the deformation of the end (38b) of the air duct (38) is restrained. Therefore, the opening area of the end (38b) of the air duct (38) can be maintained, and the connecting state between the film part (36) and the air duct (38) can be well ensured.