PURPOSE: To manufacture a unidirectional electric steel sheet excellent in magnetic properties, in the rolling stage till the thickness of a steel reaches the one of a final product after hot rolling by executing cold rolling and decarburization-primary recrystallization annealing under specified conditions.

CONSTITUTION: In the rolling stage for silicon steel stock contg. 0.01 to 0.06% C, 2 to 4% Si, 0.02 to 0.15% Mn and 0.005 to 0.1% S and/or Se and the balance substantial Fe till its sheet thickness reaches the one of a final product after hot rolling, cold rolling is executed in the temp. range of >0 to 100°C at least per pass, and in decarburization-primary recrystallization annealing, primary recrystallication is completed in the temp. range of 500 of 800°C for ≥20sec. At the time of executing the cold rolling at a low temp., the slip system at the time of deformation is limited, and by executing the raise of temp. by a small rate, the (110)<001> grains are easy to grow. As a result, the value of B8 can be improved without increasing the grain size, and the improvement of core loss can also be attained.