Abstract: An automatic wheel shaft reversing mechanism comprises a drive gear adapted to be rotatably driven by a driver unit; driven gears are provided which are movable in the axial direction of a wheel shaft and supported thereon, the driven gears alternatively meshing with the drive gear at right angles at two engaging portions, respectively; a cam portion is also provided which is adapted to be rotated by the driver unit to change over the engagement of the drive gear with the two engaging portions of the driven gears; a spring is also provided for biasing the driven gears. The driver unit, in preferred form, is a movement box unit. The reversing mechanism is usable in a variety of toy vehicles.