A glass sheet producing method, comprising the steps of: forming a glass ribbon into a sheet-like shape; annealing the glass ribbon so that internal distortion of the glass ribbon is removed; cooling the glass ribbon to room temperature; and cutting the glass ribbon into predetermined dimensions, at least the forming and the annealing being performed along with downward movement of the glass ribbon, wherein the annealing comprises: forming a curved portion by curving the glass ribbon in a width direction to thereby increase a bending resistance in an upper and lower direction of the glass ribbon, characterised in, reversing a concavo-convex direction in a front and back direction of the curved portion at least between an upper side and a lower side of a part of a region in the width direction of the glass ribbon such that the glass ribbon is curved in an upper and lower direction in a manner that directions of convex sides of the respective curved portions on an upstream side and a downstream side are reversed to each other between a back surface side and a front surface side with respect to a reversed portion, to thereby increase a bending resistance in the width direction of the glass ribbon, wherein the concavo-convex direction in the front and back direction of the curved portion is reversed with respect to the width direction of the glass ribbon. forming a glass ribbon into a sheet-like shape; annealing the glass ribbon so that internal distortion of the glass ribbon is removed; cooling the glass ribbon to room temperature; and cutting the glass ribbon into predetermined dimensions, at least the forming and the annealing being performed along with downward movement of the glass ribbon, at least the forming and the annealing being performed along with downward movement of the glass ribbon, wherein the annealing comprises: forming a curved portion by curving the glass ribbon in a width direction to thereby increase a bending resistance in an upper and lower direction of the glass ribbon, characterised in, reversing a concavo-convex direction in a front and back direction of the curved portion at least between an upper side and a lower side of a part of a region in the width direction of the glass ribbon such that the glass ribbon is curved in an upper and lower direction in a manner that directions of convex sides of the respective curved portions on an upstream side and a downstream side are reversed to each other between a back surface side and a front surface side with respect to a reversed portion, to thereby increase a bending resistance in the width direction of the glass ribbon, wherein the concavo-convex direction in the front and back direction of the curved portion is reversed with respect to the width direction of the glass ribbon. forming a curved portion by curving the glass ribbon in a width direction to thereby increase a bending resistance in an upper and lower direction of the glass ribbon, characterised in, reversing a concavo-convex direction in a front and back direction of the curved portion at least between an upper side and a lower side of a part of a region in the width direction of the glass ribbon such that the glass ribbon is curved in an upper and lower direction in a manner that directions of convex sides of the respective curved portions on an upstream side and a downstream side are reversed to each other between a back surface side and a front surface side with respect to a reversed portion, to thereby increase a bending resistance in the width direction of the glass ribbon, wherein the concavo-convex direction in the front and back direction of the curved portion is reversed with respect to the width direction of the glass ribbon.