PURPOSE: To provide a stairs ascending-descending device for a bag which can smoothly ascend and descend stairs and whose structure is simple and cost is reduced.

CONSTITUTION: A stairs ascending-descending device of a bag is provided with a belt plate-like base member 8 fixed to the bag side and a ground contact member 9 formed so as to slidingly contact with the base member 8, and the bag is moved by sliding the base member 8 on the ground contact member 9. In this stairs ascending-descending device M, when the ground contact member 9 contacts with a corner part of stairs, the base member 8 slides on the ground contact member 9, and the bag moves. Therefore, a movement of the bag is smooth, and vibration is hardly generated while getting over a single stage of stairs, and smooth ascent-descent becomes possible without being influenced by a construction material and a shape of the stairs. Since the ground contact member 9 does not rub against the stairs, the stairs are not damaged.