There is provided a grain-oriented electrical steel sheet stably having excellent magnetic characteristics and coating adhesion even when a rapid heating is conducted in a primary recrystallization annealing (decarburization annealing). Concretely, it is a grain-oriented electrical steel sheet provided on its sheet surface with a tension-applying type insulation coating constituted with a coating layer A formed on a steel sheet side and mainly composed of an oxide and a coating layer B formed on a surface side and mainly composed of glass, characterized in that a ratio R (.sub.B/.sub.A) of a tension .sub.B of the coating layer B on the surface side applied to the steel sheet to a tension .sub.A of the coating layer on the steel sheet side A applied to the steel sheet is within a range of 1.20-4.0.

A grain-oriented electrical steel sheet is a grain-oriented electrical steel sheet which does not have an inorganic coating containing forsterite as a main component and which includes: a base steel sheet containing a prescribed chemical component; a silicon-containing oxide layer provided on the base steel sheet; an iron-based oxide layer provided on the silicon-containing oxide layer; and a tension-insulation coating provided on the iron-based oxide layer, having a thickness of 1 to 3 ?m, and containing phosphate and colloidal silica as main components. When the tension-insulation coating undergoes elemental analysis using a glow discharge optical emission spectrometry in a sheet thickness direction from a surface of the tension-insulation coating, a peak Si emission intensity satisfies a prescribed requirement.

The present invention has as its object to provide grain-oriented electrical steel sheet further improved in core loss in control of magnetic domains by forming laser grooves in steel sheet after decarburization annealing and before finish annealing.

The grain-oriented electrical steel sheet according to the present invention is a grain-oriented electrical steel sheet having a plurality of grooves on the surface of the steel sheet and provided with a glass coating on that surface, which grain-oriented electrical steel sheet characterized in that an absolute value of an angle formed by a direction perpendicular to both a rolling direction and sheet thickness direction of the steel sheet and a longitudinal direction of the grooves is 0 to 40, a width W of the grooves is 20 to 300 m, a depth D of the grooves is 10 to 40 m, and a pitch P of the grooves in the rolling direction is 1.0 to 30 mm and in that the relationship of formula (1) is satisfied when a thickness of the glass coating of flat parts of the steel sheet surface (parts other than grooves) is t1 and the thickness of the glass coating at the deepest parts of the grooves is t2:

t2/t1<1.00formula (1)