To provide a steel cord improving rubber permeability while maintaining its compactness and suppressing cord strength deterioration.

The steel cord has a layer stranded structure formed with a sheath 12 composed of 1-8 sheath wire(s) Fs around a core 11, wherein the core 11 is formed of a wire bundle 13 made by mutually twisting first two core wires Fc1 at a twisting pitch P1, and one second core wire Fc2 helically wound around the wire bundle 13 at a twisting pitch P2 different from the twisting pitch P1 in the same direction of twisting the first core wires Fc1. The pitches P1 and P2 meets the following relationship: |P2-P1|/P10.25.