To provide a bag on casters which has casters simply, easily, and inexpensively mass-produced, and moves the bag lightly and silently.

A bag body 3 is moved in an upright orientation on casters 1 on its bottom of by using a grip 2. In the caster, a shaft 9 is coupled to a wheel 6 by one bearing 8. The ends of the shaft 9 are secured to the yoke 7 coupled to the bag portion 3. An outer ring 8B of the bearing 8 is fitted into a fitting groove 15 disposed at the center of the wheel 6 so that the bearing 8 is fixed. The outer diameter (A) of the shaft 9 is smaller than the inner diameter (B) of an inner ring 8A, and a pair of spacer pipes 17 are inserted into the inner ring (A). Insertion portions 17B of the spacer pipes 17 with a smaller outer diameter are inserted into the inner ring 8A of the bearing 8 from both sides and the inner ring 8A is coupled to the shaft 9. Stopper portions 17A with a greater outer diameter are arranged between the inner ring 8A and the yoke 7 to hold the bearing 8 at a constant position of the shaft 9.