Grain-oriented electrical steel sheet and manufacturing method thereof

A grain-oriented electrical steel sheet having a composition comprising 0.8 mass % to 7 mass % of Si, 0.05 mass % to 1 mass % of Mn, 0.0005 mass % to 0.0080 mass % of B, 0.005 mass % or less of each of Al, C, N, S and Se, and a balance comprising Fe and inevitable impurities, and having a glass coating film, comprising a composite oxide mainly comprising forsterite on a steel sheet surface, wherein:

• a peak position of B in emission intensity from the steel sheet surface is different from and deeper than a peak position of Mg in emission intensity when glow discharge optical emission spectrometry (GDS) is performed, and
• out of peaks of B in emission intensity observed by the glow discharge optical emission spectrometry (GDS), a peak occurrence time tB of a peak that is the farthest from the steel sheet surface is expressed by the following Expression (1):
• tMg×1.6≤tB≤tMg×5 (1)
• where tMg represents a peak occurrence time of Mg, and the peak position of B, Mg, the values tB and tMg are measured by the GDS on a surface of a secondary coating film containing 26 to 38 mass % of colloidal silica, 4 to 12 mass % of one type or two types selected from the group consisting of chromium anhydride and chromate, and a balance comprising aluminum biphosphate, and having a thickness of not less than 1 μm nor more than 2 μm.