A rubber product-reinforcing metallic cord is provided which comprises three to five metallic filaments, which shows a high degree of penetration of rubber without reducing compressive rigidity, and which can be manufactured at low facility and production costs. A rubber product-reinforcing metallic cord 7 is formed by twisting together a pre-strand 6 comprising a first metallic filament 1 and a second metallic filament 2 helically wrapped around the first filament 1, and a fifth metallic filament 3 (or 5) with a twist pitch P. The metallic cord 7 may be formed by twisting together two of such pre-strands, or by twisting together two of such pre-strands and the fifth metallic filament.