A vehicle seat has a seat cushion, a seat bag, a lock mechanism and a belt anchor. The seat cushion has a cushion frame. The seat bag has a back frame that is rotatably connected to the cushion frame. The lock mechanism is provided on each of the frames, and latch-connected to a striker at a vehicle side. The belt anchor is provided on one of the two frames, and is fastened with a seat belt. A force transmission structure is provided between the two frames, in which when the seat belt is pulled forward, so that a member between the belt anchor and the striker is deformed, a member at a side of the one frame pushes a member at a side of the other frame, thereby force is transmitted from the one frame side to the other frame side.