A method for manufacturing a grain-oriented electrical steel sheet, the method comprising, in sequence: subjecting a steel slab to hot rolling to obtain a hot rolled sheet, the steel slab comprising a chemical composition consisting of, in mass%, Si: 2.0% to 4.5% and Mn: 0.005% to 1.0% and at least one of Sb: 0.010% to 0.200%, Sn: 0.010% to 0.200%, Mo: 0.010% to 0.100%, Cu: 0.010% to 0.100%, and P: 0.010% to 0.080%, optionally at least one of Ni: 0.010% to 1.50%, Cr: 0.01% to 0.50%, Bi: 0.005% to 0.50%, Te: 0.005% to 0.050%, and Nb: 0.0010% to 0.0100%, optionally C: 0.010% to 0.100%, Al: 0.01% or less, N: 0.005% or less, S: 0.005% or less, and Se: 0.005% or less or optionally C: 0.010% to 0.100% and at least one of (i) Al: 0.010% to 0.050% and N: 0.003% to 0.020%, and (ii) S: 0.002% to 0.030% and/or Se: 0.003% to 0.030%, and the balance being Fe and incidental impurities; subjecting the hot rolled sheet to hot band annealing as required; subjecting the hot rolled sheet to cold rolling once or cold rolling twice or more with intermediate annealing in between, to obtain a cold rolled sheet with a final sheet thickness; subjecting the cold rolled sheet to primary recrystallization annealing to obtain a primary recrystallized sheet; applying an annealing separator onto a surface of the primary recrystallized sheet and then subjecting the primary recrystallized sheet to final annealing for secondary recrystallization, to obtain a secondary recrystallized sheet that has a forsterite film on a surface of a steel substrate; measuring a retention time T (hr) which is a time required after the final annealing to reduce a temperature of the secondary recrystallized sheet from 800°C to 400°C; and subjecting the secondary recrystallized sheet to flattening annealing for 5 seconds or more and 60 seconds or less at a temperature of 750°C or higher; wherein during the flattening annealing, a line tension Pr (MPa) on the secondary recrystallized sheet is controlled based on the measured retention time T (hr) to satisfy the following conditional Expression, so that a dislocation density near crystal grain boundaries of the steel substrate is 1.0 × 10 13 m -2 or less: Pr ≤ − 0.075 ⁢ T + 18 where T > 10; 5 < Pr wherein during cooling of the secondary recrystallized sheet after the final annealing, the secondary recrystallized sheet is held for 5 hours or longer at a predetermined constant temperature from 800°C to 400°C. subjecting a steel slab to hot rolling to obtain a hot rolled sheet, the steel slab comprising a chemical composition consisting of, in mass%, Si: 2.0% to 4.5% and Mn: 0.005% to 1.0% and at least one of Sb: 0.010% to 0.200%, Sn: 0.010% to 0.200%, Mo: 0.010% to 0.100%, Cu: 0.010% to 0.100%, and P: 0.010% to 0.080%, optionally at least one of Ni: 0.010% to 1.50%, Cr: 0.01% to 0.50%, Bi: 0.005% to 0.50%, Te: 0.005% to 0.050%, and Nb: 0.0010% to 0.0100%, optionally C: 0.010% to 0.100%, Al: 0.01% or less, N: 0.005% or less, S: 0.005% or less, and Se: 0.005% or less or optionally C: 0.010% to 0.100% and at least one of (i) Al: 0.010% to 0.050% and N: 0.003% to 0.020%, and (ii) S: 0.002% to 0.030% and/or Se: 0.003% to 0.030%, and the balance being Fe and incidental impurities; subjecting the hot rolled sheet to hot band annealing as required; subjecting the hot rolled sheet to cold rolling once or cold rolling twice or more with intermediate annealing in between, to obtain a cold rolled sheet with a final sheet thickness; subjecting the cold rolled sheet to primary recrystallization annealing to obtain a primary recrystallized sheet; applying an annealing separator onto a surface of the primary recrystallized sheet and then subjecting the primary recrystallized sheet to final annealing for secondary recrystallization, to obtain a secondary recrystallized sheet that has a forsterite film on a surface of a steel substrate; measuring a retention time T (hr) which is a time required after the final annealing to reduce a temperature of the secondary recrystallized sheet from 800°C to 400°C; and subjecting the secondary recrystallized sheet to flattening annealing for 5 seconds or more and 60 seconds or less at a temperature of 750°C or higher; wherein during the flattening annealing, a line tension Pr (MPa) on the secondary recrystallized sheet is controlled based on the measured retention time T (hr) to satisfy the following conditional Expression, so that a dislocation density near crystal grain boundaries of the steel substrate is 1.0 × 10 13 m -2 or less: Pr ≤ − 0.075 ⁢ T + 18 where T > 10; 5 < Pr wherein during cooling of the secondary recrystallized sheet after the final annealing, the secondary recrystallized sheet is held for 5 hours or longer at a predetermined constant temperature from 800°C to 400°C.