To produce an ultrahigh tensile strength steel strip and an ultrahigh tensile strength electric resistance welded tube excellent in durability of ≥980N/mm2 tensile strength by solving a technological problem in the conventional technology of hydrogen delayed cracking or deterioration in strength caused by corrosion and to provide a method for producing the same.

This ultrahigh tensile strength steel strip excellent in durability and having ≥980N/mm2 tensile strength consists of a steel contg., by weight, 0.1 to 0.19% C, 1 to 2% Mn, 0.05 to 0.5% Cu, ≤0.1% P, ≤0.01% S, ≤0.005% N, and the balance substantial iron. A metallic structure contains martensite of 40 to 100% fractional rate, and the cumulative equivalent strain defined by following formula after quenching is regulated to 0.002 to 0.2. =Σ((t/d)×(the number of times of bending)), where (t) denotes the plate thickness (mm) of the steel plate and (d) denotes the bend diameter (mm).