To provide a steel cord for reinforcement of a rubber product that improves the cord strength by preventing the occurrence of advance breaking of the outermost layer filaments of the steel cord having a multi-twisted structure, and a pneumatic tire which uses the same as a reinforcing material.

The steel cord for reinforcement of the rubber product has the multi-twisted structure formed by twisting multiple strands having a layer-twisted structure of multiple twisted steel filaments, with the ratio dc/ds of the diameter dc of outermost layer sheath filaments which form the outermost layer sheath of the core strands and the diameter ds of outermost layer sheath filaments which form the outermost layer sheath of the sheath strands being 1.05-1.25.