To suppress the deterioration and slip of a belt member caused by tensely installing the member in an attitude suitable for reducing the size of a device such that the member is wrapped around a tensely installed member at a large curvature or reversely bent.

This belt member 1 uses movement stopping projected parts 1b having cutouts 1c extending from the upper ends of projections to the lower end thereof arranged in the circumferential direction of a belt. Also, the belt member 1 on which a plurality of recessed and projected parts alternately arranged in the circumferential direction of the belt in place of the movement stopping projected parts 1b or the belt member 1 on which a plurality of hollow parts are formed along the belt may be used. Thus, the belt member 1 can be wrapped around a tensely installed roller 2 at the large curvature or reversely bent without applying a large burden on the movement stopping projected part. As a result, the deterioration and slip of the belt caused by tensely installing the belt in the attitude suitable for reducing the size of the device can be suppressed.