A grain-oriented electrical steel sheet, comprising: a steel sheet having a steel sheet surface in which a groove, which extends in a direction intersecting a rolling direction and of which a groove depth direction becomes a sheet thickness direction, is formed, wherein the steel sheet consists of, as chemical components in terms of mass fraction, Si: 0.8% to 7.0%, C: greater than 0% and equal to or less than 0.085%, acid-soluble Al: 0% to 0.065%, N: 0% to 0.012%, Mn: 0% to 1%, Cr: 0% to 0.3%, Cu: 0% to 0.4%, P: 0% to 0.5%, Sn: 0% to 0.3%, Sb: 0% to 0.3%, Ni: 0% to 1%, S: 0% to 0.015%, Se: 0% to 0.015%, and the remainder including Fe and unavoidable impurities, wherein the steel sheet has a thickness of 0.15 mm to 0.35 mm, wherein the groove includes an inclined portion that is inclined from the steel sheet surface to a bottom portion of the groove at a groove end (31a, 31b) in a longitudinal groove direction that is a direction in which the groove extends, when an average value of a depth of the groove in the sheet thickness direction from a height of the steel sheet surface at a central portion in the longitudinal groove direction is set as an average groove depth D in a unit of μm, the average groove depth D being 10 μm to 50 μm, a straight line, which connects a first point at which the depth of the groove in the sheet thickness direction from the height of the steel sheet surface becomes 0.05×D, and a second point at which the depth of the groove in the sheet thickness direction from the height of the steel sheet surface becomes 0.50×D, at the inclined portion is set as a groove end straight line, an angle made by the steel sheet surface and the groove end straight line is set as a first angle θ in a unit of °, and in a case where the groove is seen on a groove-width-direction cross-section perpendicular to the longitudinal groove direction at the central portion of the groove, an average value of a groove-width-direction length, which is a length of a line segment connecting two points (33, 34) at which a depth of the groove in the sheet thickness direction from the height of the steel sheet surface in a contour of the groove on the groove-width-direction cross-section becomes 0.05×D, is set as an average groove width W of the groove in a unit of μm, an aspect ratio A obtained by dividing the average groove depth D by the average groove width W, and the first angle θ satisfy the following Expression, wherein in the steel sheet, a grain size in the steel thickness direction of a crystal grain that is in contact with the groove is 5 μm or greater, the grain size of the crystal grain representing an equivalent circle diameter obtained in accordance with ASTM E112 or an electron back scattering diffraction pattern (EBSD) method. θ < − 21 × A + 77 a steel sheet having a steel sheet surface in which a groove, which extends in a direction intersecting a rolling direction and of which a groove depth direction becomes a sheet thickness direction, is formed, wherein the steel sheet consists of, as chemical components in terms of mass fraction, Si: 0.8% to 7.0%, C: greater than 0% and equal to or less than 0.085%, acid-soluble Al: 0% to 0.065%, N: 0% to 0.012%, Mn: 0% to 1%, Cr: 0% to 0.3%, Cu: 0% to 0.4%, P: 0% to 0.5%, Sn: 0% to 0.3%, Sb: 0% to 0.3%, Ni: 0% to 1%, S: 0% to 0.015%, Se: 0% to 0.015%, and the remainder including Fe and unavoidable impurities, wherein the steel sheet has a thickness of 0.15 mm to 0.35 mm, wherein the groove includes an inclined portion that is inclined from the steel sheet surface to a bottom portion of the groove at a groove end (31a, 31b) in a longitudinal groove direction that is a direction in which the groove extends, when an average value of a depth of the groove in the sheet thickness direction from a height of the steel sheet surface at a central portion in the longitudinal groove direction is set as an average groove depth D in a unit of μm, the average groove depth D being 10 μm to 50 μm, a straight line, which connects a first point at which the depth of the groove in the sheet thickness direction from the height of the steel sheet surface becomes 0.05×D, and a second point at which the depth of the groove in the sheet thickness direction from the height of the steel sheet surface becomes 0.50×D, at the inclined portion is set as a groove end straight line, an angle made by the steel sheet surface and the groove end straight line is set as a first angle θ in a unit of °, and in a case where the groove is seen on a groove-width-direction cross-section perpendicular to the longitudinal groove direction at the central portion of the groove, an average value of a groove-width-direction length, which is a length of a line segment connecting two points (33, 34) at which a depth of the groove in the sheet thickness direction from the height of the steel sheet surface in a contour of the groove on the groove-width-direction cross-section becomes 0.05×D, is set as an average groove width W of the groove in a unit of μm, an aspect ratio A obtained by dividing the average groove depth D by the average groove width W, and the first angle θ satisfy the following Expression, wherein in the steel sheet, a grain size in the steel thickness direction of a crystal grain that is in contact with the groove is 5 μm or greater, the grain size of the crystal grain representing an equivalent circle diameter obtained in accordance with ASTM E112 or an electron back scattering diffraction pattern (EBSD) method.