PURPOSE: To manufacture a nonrefined high tensile steel with a high strength level and superior low temp. toughness by hot rolling a steel contg. a specified percentage of metallic elements under specified conditions followed by cooling at a specified cooling rate.

CONSTITUTION: A steel contg., by wt., 0.03W0.15% C, 0.03W0.60% Si, 0.5W 2.0% Mn, 0.005W0.10% Nb and ≤0.06% sol. Al of further contg. ≤0.15% V and one or two kinds among ≤0.5% each of Ni, Cr, Cu and Mo is heated to ≥1,050°C, rolled at ≥50% total reduction ratio in an austenite recrystallization temp. zone, and further rolled at ≥70% total reduction ratio in a temp. zone under the austenite recrystallization temp. The final finish rolling is carried out at the Ar3 point or above. The rolled plate is cooled from the Ar3 point or above to 400W 550°C under the condition in which the average cooling rate at a central part in the through thickness direction exceeds 30°C/sec, and then it is air cooled.