To provide a cord for reinforcing rubbers, which is high in fiber cord physical properties and is simultaneously excellent in rubber adhesion performance such as peeling-resistant adhesion and drawing-resistant adhesion in a high temperature atmosphere.

The cord for reinforcing the rubbers is composed of synthetic fibers, wherein 20 to 80 wt.% of the synthetic fibers constituting the cord are aliphatic polyketone fibers; a pre-treating agent containing an epoxy compound and a resorcinol-formalin-latex-based adhesion treating agent are adhered to the surface of the cord; and the adhesion treating agent contains an inorganic filler. In addition, the inorganic filler is preferably carbon black or silica, and the synthetic fibers constituting the cord preferably contains polyester fibers or aromatic polyamide fibers. It is further preferable that the aromatic polyamide fibers are para-type aromatic copolyamide fibers.