PURPOSE: To obtain an extra thin cold-rolled soft steel plate having excellent ductility and deep drawability by containing the specific quantities of C, Mn, S, Al, N, and O in a steel slab, hot-rolling this steel slab, cold-rolling primarily it at the specific cold-rolling rate, cold-rolling secondarily it at the specific cold-rolling rate and next executing control-annealing to it.

CONSTITUTION: The composition of steel slab is wt% of 0.001W0.006% C, 0.03W0.25% Mn, 0.001W0.015% S, 0.002W0.015% Al, 0.002W0.007% N, 0.001W0.005% O and remaining part of Fe with inevitable impurities. This steel slab is finished under hot- rolling at Ar3 point or more for the finishing temp. and wound at 650W750°C winding temp. and acid pickling is executed to the hot-rolled coil obtd. Next, the primary cold-rolling is executed at 30W85% the cold-rolling rate and the primary annealing is executed by open coil annealing. In succession, the secondary cold-rolling is executed at 60W95% the cold-rolling rate and the secondary annealing is executed at 550W650°C by tight coil annealing (the low temp. box annealing). By this method, the extra thin (≤0.5mm) cold-rolled steel plate having high ductility and deep drawability is obtd.