A filament winding apparatus winds, around a workpiece, a fiber bundle formed by bundling a plurality of fibers. The filament winding apparatus includes a widening roller that rotates while making contact with the fiber bundle that is being conveyed. The widening roller has, provided on the peripheral surface, a plurality of projecting ridges extending in the axial direction, the projecting ridges being arranged side by side in the circumferential direction. The projecting ridges make contact with the fiber bundle to thereby widen the fiber bundle.