To develop a core roller that can be readily pulled out of a wound- around cloth, paper or other sheets even when the roller is wound with cloth, paper and the like, and provide a roller that can be pulled out of the cloth, paper or the like wound around by contracting the diameter of the roller, for example, the roller is used as a winding-up roller for a weaving machine.

The trunk body of the roller is built up from body parts divided into two or more in the axis direction and a diameter-expanding and contracting means 2 is inserted between the divided body parts or inserted into the inside of the body parts and is made expandable.