An optical fiber winding bobbin includes: a main winding body portion having an outer circumferential surface around which an optical fiber is wound; and a main winding flange that is disposed on one end portion of the main winding body portion in an axial direction and that protrudes radially outward. The main winding flange includes: an inner circumferential edge portion connected to the main winding body portion; a central portion; and an outer circumferential portion having a thin portion and positioned outward from the central portion in a radial direction. An axial thickness of the thin portion is smaller than an axial thickness of the inner circumferential edge.