PURPOSE: To prevent an irregular arrangement of a hard steel wire which is a component of a bead wire for a pneumatic tire and to prevent presence of an acutely angled portion on an outer periphery of the bead wire by forming a cross section of a hard steel wire into an elliptic shape.

CONSTITUTION: A bead wire includes a plurality of wound turns of a hard steel wire 1 which has a cross section of an elliptic shape including a pair of upper and lower opposed parallel linear portions 2 and a pair of leftwardly and rightwardly convexted arcuate portions 3. With this elliptic shape in cross section, thickness T of the hard steel wire 1 has a dimension of 40W80% of its width W, and cross sectional area of the bowshaped portions 3a is substantially 10W40% of the whole cross sectional area of the hard steel wire 1 with an arc of each bow shape having a radius of curvature substantially similar to the radius of an original wire. The hard steel wire 1 is dipped into an adhesive resin tank or coated by plating as occasion calls, and then is coated with rubber. The hard steel wire 1 is wound in layer on a former of a known winding machine to thereby form a bead wire 10 which has, for example, a generally rectangular cross section.