Abstract: In a gearbox device, a housing is formed with a hole-confining wall portion. A shaft is mounted rotatably in the hole-confining wall portions. An oil seal unit is mounted in the housing to provide a liquid tight seal between the shaft and the hole-confining wall portion. The oil seal unit includes an annular rubber seal member and an annular ceramic member. The ceramic member is disposed radially and inwardly of the rubber seal member and is in contact with the rubber seal member. The ceramic member disposed in the rubber seal member is sleeved on and is fixed to the shaft. The rubber seal member disposed outwardly of the ceramic member is fixed to the hole-confining wall portion.