Grain-oriented electrical steel sheet and manufacturing method thereof

A grain-oriented electrical steel sheet comprising:

• a base steel sheet having plural grooves on a surface;
• and
• a glass film formed on the surface of the base steel sheet and on the plural grooves, the content rate of forsterite in the glass film being 70% by volume or more,
• wherein:
• the grain-oriented electrical steel sheet has an iron loss, W17/50, of 0.8 W/kg or less,
• an angle that a groove longitudinal direction makes with a direction orthogonal to a rolling direction and a sheet thickness direction of the base steel sheet is 0° to 40°,
• a width of a groove of the plural grooves forming the angle is 20 to 300 μm, at an outermost surface level of the base steel sheet,
• a depth of the groove forming the angle is 10 to 40 μm,
• intervals of the grooves forming the angle in the rolling direction are 2 to 30 mm, and
• in viewing a region including the grooves in a cross section orthogonal to the groove longitudinal direction,
• a point present on a profile line of the glass film and present at a highest location in the sheet thickness direction is defined as a peak point,
• a straight line passing through the peak point and parallel to a groove width direction orthogonal to the sheet thickness direction in the cross section is defined as a reference line,
• a point present on a boundary line between the glass film and the base steel sheet and present at a lowest location in the sheet thickness direction is defined as a deepest point,
• a point present on the boundary line and present at the highest location in the sheet thickness direction in a region having the deepest point in a center and having a length of 2 m in the groove width direction is defined as a shallowest point, and
• a relationship between a shortest distance A between the reference line and the deepest point and a shortest distance B between the reference line and the shallowest point satisfies Expression (1),
• 0.1 μm≤A−B≤5.0 μm (1).