To provide a bag with casters which allows smooth passage through a rough road while traveling, not making contact with passing people even in a crowd, and avoiding collision with the people.

The bag with casters has a rectangular parallelepiped shape, has a wheel structure to be inclined to have an increased height at the front and a reduced height at the rear relative to the traveling direction, and is travels while directing a narrow surface to the travelling direction. Spring casters are provided at front wheels, and the main load of the bag is shifted to rear wheels provided on the outside of the back surface owing to the inclination and the spring casters. Since a user always uses the bag being inclined, the load of things put in the bag is spontaneously shifted toward the rear wheels. The inclination facilitates horizontal swing of a handle vertically attached to the rear surface with the rear wheels or wheel shafts as the fulcrum. Accordingly, the bag is easy to turn in direction, and provides safe and smooth travel thereof without falling down.