PURPOSE: To produce a steel cord for reinforcing a rubber article excellent in corrosion propagation resistance without deteriorating the cord strength in a steel cord of a [1+(n)] structure[(n) is 6-8] and a pneumatic tire reinforced with the steel cord.

CONSTITUTION: This steel cord for reinforcing a rubber article is obtained by preforming a core filament into a waveform in the steel cord for reinforcing the rubber article in which one spiral filament 3 is arranged around sheath filaments 2 by a [1+(n)] structure [(n) is 6, 7 or 8]. In the steel cord, the preforming ratio R (=L/D) represented by the ratio of the amplitude L of the wavy preforming to the wire diameter (d) of the core filament is respectively 0.08≤R≤1.4 when (n) is 6; 0.45$ R≤1.8 when (n) is 7 and 0.95≤R≤2.3 when (n) is 8. Furthermore, the sheath filaments are non-twist ones.