PURPOSE: To secure the stable curve travel of a travelling truck by connecting the right and left wheels of the travelling truck to each other by arms, and forming such wheel structure that the wheels on one side are supported rotatably in the right and left directions by the frame of the travelling truck, whereas the wheels on the other side follow the wheels on one side.

CONSTITUTION: In a travelling truck provided with driving wheels 2, 2 and driven wheels 3, 3 with motors 2a connected to a chassis 10, the driving wheels 2 and driven wheels 3 disposed on the right and left sides of the chassis 10 are disposed at arms 11 respectively with a gap L between two rails R. Each driving wheel 2 is supported rotatably in the right and left directions by the chassis 10 through a bearing 13 provided at the supporting part 12 of the driving wheel 2. A roller 3a is rotatably supported above the driven wheel 3, and the driven wheel 3 is supported by the chassis 10 through this roller 3a. A plate 10a is further provided at a contact face between the roller 3a and the chassis 10 so as to minimize the rotational resistance of the roller 3a.