RUBBER ARTICLE REINFORCING STEEL WIRE AND RUBBER ARTICLE USING SAME

Provided are a rubber article reinforcing steel wire that is superior in bending fatigue properties to the related art and has a flat cross-sectional shape, and a rubber article using the wire. In a rubber article reinforcing steel wire 10, a major diameter and a minor diameter are substantially perpendicular to each other. Assuming that the major diameter is W, the minor diameter is T, a straight line that passes through a center of the major diameter in a width direction and is parallel to a minor diameter direction is L1, a straight line that passes through a center of the minor diameter in a width direction and is parallel to a major diameter direction is L2, an intersection point of the L1 and the L2 is a center point C, a region within a half of a distance from the center point C to a surface is a central region Rc, and a region outside the central region Rc is a surface layer region Rs, a Vickers hardness Hvc of the central region Rc is more than a Vickers hardness Hvs of the surface layer region Rs; and assuming that a Vickers hardness on the L1 in the surface layer region Rs is Hv1, and a Vickers hardness on the L2 in the surface layer region Rs is Hv2, relationships represented by Hvc - Hv1 ‰¤ 150, Hvc - Hv2 ‰¤ 150, Hv1/Hvc × 100 ‰¥ 85.11, and Hv2/Hvc × 100 ‰¥ 79.84 are satisfied.