PURPOSE: To produce stock for an ultrahigh magnetic flux density grain oriented silicon steel sheet extremely high in magnetic flux density by preparing steel stock having a specified component of compsn. in which the content of acid soluble Al, N and Bi is prescribed.

CONSTITUTION: The stock (ingot, slab or hot rolled steel) contg., by weight, 0.03 to 0.15% C, 2.5 to 4.0% Si, 0.02 to 0.30% Mn, 0.005 to 0.040% S, 0.010 to 0.065% acid soluble Al and 0.0030 to 0.0150% N, contg., at need, 0.05 to 0.50% Sn and 0.01 to 0.10% Cu and furthermore contg. 0.0005 to 0.05% Bi, and the balance Fe with inevitable impurities is prepd. In this way, the Goss azimuth is highly developed, by which the stock for an ultrahigh magnetic flux density grain oriented silicon steel sheet having about 1.95 to 2T magnetic flux density can be obtd.