PURPOSE: To make drawability and ductility much better than those of conventional products and further obtain a high tensile cold rolled steel plate of excellent deep drawability at a low yield point by adding proper smounts of P, Si and Mn to Nb- contg. extra low carbon Al killed steel.

CONSTITUTION: A steel plate obtained by hot rolling, cold rolling and box annealing of a steel ingot or slab consisting of 0.002W0.015 C by %, ≤1.2 Si, 0.05W 0.8Mn, 0.02W0.08 P, ≤0.02 S, ≤0.01 N, ≤0.008 O, ≤0.10 acid soluble Al, and ≥1.8 times N, 3×CW(8C+0.02) Nb, and the balance Fe and unavoidable impurities. Here, the P is essential for improving strength. Below the lower limit thereof, the strength is low, and above the upper limit, weldability degrades. The Si can be compounded together with the above-described amount of P with 38W45kg/mm class steel, but if is in excess of the upper limit, the degradation in an (r) value and elongation is considerable. The Mn can also be compounded together with the P as with the Si. Below the lower limit, S fixing is insufficient and brittleness increases. In excess of the upper limit, the (r) value and elongation are considerably reduced.