A centering member 20 is pressed downward using an elastic member 28; the centering member 20 is provided at the bottom of a platform 14. A plate 26 receiving an upper end of the elastic member 28 is positioned high while the platform 14 is elevating. The plate 26 is positioned low after the platform 14 has been completely elevated. While the platform 14 is elevating or lowering, a pressing force on the centering member 20 is reduced. After the platform 14 has been completely elevated, the pressing force is weakened. The present invention suppresses vibration of the platform having been completely elevated. The present invention also prevents the article from exerting a strong upward force on the platform via a pressing member when the article is loaded or unloaded.