PROBLEM TO BE SOLVED: To obtain a high strength steel pipe for a line pipe, excellent in DWTT performance and HIC resistance. SOLUTION: The steel pipe for a line pipe comprises 0.02-0.06% C, ≤0.5% Si, 0.8-1.6% Mn, ≤0.008% P, ≤0.0008 S, ≤0.08% Al, 0.005-0.035% Nb, 0.005-0.025% Ti, 0.0005-0.0030% Ca, ≤0.0030% O and one or more kinds of ≤0.5% Cu, ≤1% Ni, ≤0.5% Cr, ≤0.5% Mo, ≤0.1% V and the balance Fe with inevitable impurities, wherein a CP value=4.46C(%)+2.37Mn(%)/6+ä1.18Cr(%)+1.95Mo(%)+1.74V(%)}/5+ä1.74Cu(%)+1.7Ni(%)}/15+22.36P(%) is ≤0.95, and an IP value=[Ca(%)-ä0.18+130Ca(%)}*O(%)]/1.25S(%) is 1.5-2.8, and the steel pipe has, as metallurgical structure, two phase structure of ferrite-bainite having ≥50% ferritic phase in an area fraction, wherein the average grain diameter of the ferritic phase is ≤5 μm and the average aspect ratio of the bainitic phase is ≤6.0. COPYRIGHT: (C)2010,JPO&INPIT