A first wheel supporting portion of a stacker crane is fixed to a travelling vehicle main body to be pivotable in the horizontal direction. A first drive wheel is supported by the first wheel supporting portion and is able to contact one side surface of a lower guide rail. A lock mechanism fixes the first wheel supporting portion to the travelling vehicle main body so that the first wheel supporting portion cannot pivot. A second wheel supporting portion is fixed to the travelling vehicle main body to be capable of pivoting horizontally. A second drive wheel is supported by the second wheel supporting portion and is able to contact with another side surface of the lower guide rail. A pressing mechanism presses the first and second wheel supporting portions such that a distance between the first wheel supporting portion and the second wheel supporting portion is reduced, to cause the first and second drive wheels to laterally clamp the lower guide rail. Pressing of the pressing mechanism is capable of being released.