PURPOSE: To provide a rubber reinforcing hose wire heightened in the wire charging degree by flattening round wire appropriately and improved in flexibility as well as in pressure withstanding property.

CONSTITUTION: Plural hose wires 1, 11 are spirally wound and embedded in a rubber hose so as to form wire-reinforced layers 10, 20. In such a rubber reinforcing hose wire, the hose wires 1, 11 has upper and lower plane parts 2, 12 formed by flattening round wires W, and the flat ratio D2/D1 of the minor axis D2 to the major axis D1 of the cross section of the upper and lower plane parts 2, 12 is set in a range of 99-25%. The wire charging degree of the wire- reinforced layers 10, 20 is then set to 78.5% or more.