PURPOSE: To obtain surely and stably a unidirectional silicon steel plate having excellent magnetic characteristics by subjecting a hot-rolled plate of a silicon steel plate having a prescribed compsn. to two times of cold rolling with intermediate annealing inbetween and subjecting the cold rolled steel plate having the final thickness to decarburization and annealing then coating an annealing separating agent contg. an S compd. thereon by a specific method and subjecting the same to final annealing.

CONSTITUTION: A silicon steel material contg., by weight, ≤0.06% C, 2.0W4.0% Si, 0.02W0.15% Mn, and 0.008W0.080% S or/and Se is hot-rolled. The resulted hot-rolled plate is subjected to two times of cold rolling with intermediate annealing in-between and the cold-rolled plate having the final thickness is subjected to decarburization and annealing. The magnetic permeability in the rolling direction of the cold rolled plate is measured and an annealing separating agent contg. an S compd. at the amt. of addition adjusted according to said value is coated on the plate which is then subjected to final annealing. As a result, the unidirectional silicon steel plate having stable and excellent magnetic characteristics is obtd. while high productivity is maintained.