A tire bead core has an annular body formed by annularly winding and bundling one bead wire in the form of a quadrangle in cross section which has two pairs of opposing sides substantially parallel to each other. The annular body comprises a plurality of winding portions radially stacked, each of which comprises sections of the bead wire annularly wound so as to align in a widthwise direction of the bead core. A winding portion of the annular body located radially outward is displaced to one side of the widthwise direction with respect to a winding portion of the annular body located radially inward.