A seat unit includes a first seat frame and a second seat frame. The first seat frame is connected with a drive carrier and includes at least one first mounting portion. The second seat frame includes wheel frames and a mounting frame fixedly connected with the wheel frames. Each wheel frame is mounted with an auxiliary wheel. A space is defined between the mounting frame and the wheel frames. The drive carrier is located in the space. The mounting frame includes at least one second mounting portion. One of the first mounting portion and the second mounting portion is a rod, and the other is a receiving portion. The rod is movably inserted through the receiving portion. When the second seat frame is displaced relative to the first seat frame, the auxiliary wheels of the wheel frames can move together relative to the drive wheels of the drive carrier.
