To provide a bag having running rollers and shoulder belts designed to keep clean the clothing of the user when shouldered.

A gag G has rollers R beneath a bottom T of a bag body F enabling to carry it over by pulling or pushing on. It also has a cover W to cover at least a part of a back face B and a pair of shoulder belts 30, 30, of which each one end is glued to the upper part of the back face B. Belts 30, 30 are set to fold inside either in a pocket 14 processed on the back face B or in a space between the back face B and the cover W lined in and covering upper part of the back face B. The cover W is put in the manner that its upper part remains glued and covers the back face B while its lower part is made to cover the back or faces 40 of the rollers R touching the user when shouldered, once its upper toggle is removed off and unfolded downward, and made detachable onto the bottom T of the bag body F.