PURPOSE: To enable an electric motor car to return by way of easily reversing its direction on a turn table after the small electric motor car travelling on a rail laid underground moves and to enable another electric motor car to pass on the turntable.

CONSTITUTION: On the upper surface center of a base 50 having a guide member 53 to guide along a rail (i) in an underground pit (g) on the lower surface, a central shaft 54 is provided and a plural number of guide rings are concentrically provided on its circumference, a spherical body 56 is put between each of the guide rings 55 and a rotating plate 52 is provided on them free to rotate, a rail member 57 corresponding to the underground pit rail (i) is provided on the rotating plate 52, and inclined car passages 63 are provided on both sides of the rotating plate on the upper surface of the base 50. It is possible to provide casters with proper intervals on the lower surface of the rotating plate 52 to provide the rotating plate 52 on the base 50 free to rotate.