A method of manufacturing a grain-oriented electrical steel sheet is provided. When irradiating the surface of a grain-oriented electrical steel sheet having a sheet thickness t with an electron beam in a direction intersecting a rolling direction, the irradiation energy E(t) of the electron beam is adjusted to satisfy Ewmin(0.23)×(1.61−2.83×t (mm))≤E(t)≤Ewmin(0.23)×(1.78−3.12×t (mm)) (Expression (1)) using the value of the irradiation energy Ewmin(0.23) that minimizes iron loss for material with a sheet thickness of 0.23 mm.