To provide a winding core for a winding device capable of easily pulling out a rolled belt-like article.

A winding core 1 for a winding device has a plurality of flexible wire material 3 closely arranged at intervals capable of mutually inserting a rolled belt-like article 2 and a shaft body 4 supporting the plurality of flexible wire materials 3. In the winding core 1 for the winding device, when the belt-like article 2 is spirally wound around the plurality of flexible wire materials 3, a force by which the belt-like article 2 fastens the flexible wire materials 3 can be released as a force elastically deforming the flexible wire materials 3. Gaps are secured between the flexible wire materials 3 and the rolled belt-like article 2, or a frictional force between them can be reduced, and thereby, the rolled belt-like article 2 can easily be pulled out of the plurality of flexible wire materials 3.