A method for manufacturing a thick-walled high-toughness high-strength steel plate having a thickness of 100 mm or more, a yield strength of 620 MPa or more, and comprising, on a mass percent basis, C: 0.08% to 0.20%, Si: 0.40% or less, Mn: 0.5% to 5.0%, P: 0.010% or less, S: 0.0050% or less, Cr: 3.0% or less, Ni: 0.1% to 5.0%, Al: 0.010% to 0.080%, N: 0.0070% or less, and O: 0.0025% or less, following formulae and being satisfied, optionally at least one of Cu: 0.50% or less, Mo: 1.50% or less, V: 0.400% or less, Nb: 0.100% or less, Ti: 0.005% to 0.020%, Mg: 0.0001% to 0.0050%, Ta: 0.01% to 0.20%, Zr: 0.005% to 0.1%, Y: 0.001% to 0.01%, B: 0.0030% or less, Ca: 0.0005% to 0.0050%, and REM: 0.0005% to 0.0100%, a remainder being Fe and incidental impurities, and comprising a toughness (vE-40) of 70 J or more at -40°C in the surface portion of the base metal: Ceq IIW = C + Mn / 6 + Cu + Ni / 15 + Cr + Mo + V / 5 ≥ 0.65 C L − C / C L × 100 ≥ 30 wherein C L is defined by the following formula: C L = 0.2 − − 0.1 × 0.2 − Si − 0.03 × 1.1 − Mn − 0.12 × 0.2 − Cu − 0.11 × 3 − Ni + 0.025 × 1.2 − Cr + 0.1 × 0.5 − Mo + 0.2 × 0.04 − V − 0.05 × 0.06 − Al wherein element symbols in the formulae denote the respective alloy component contents (% by mass), and in the absence of an element the element symbol is denoted by 0, and wherein a reduction of area in a thickness direction at half the thickness of the plate, which is the percentage of the difference between the minimum cross-sectional area after a round bar tensile test specimen including the half-thickness portion of the steel plate in the thickness direction is broken in a tensile test and the original cross-sectional area relative to the original cross-sectional area, is 40% or more, wherein the method comprises: heating steel to 1200°C to 1350°C, hot-forging the steel at a cumulative reduction of 25% or more, heating the steel to an Ac3 temperature or more and 1200°C or less, hot-rolling the steel at a cumulative rolling reduction of 40% or more, leaving the steel to cool, reheating the steel to the Ac3 temperature or more and 1050°C or less, rapidly cooling the steel from the Ac3 temperature or more to a lower temperature, which is both 350°C or less and an Ar3 temperature or less, and tempering the steel at a temperature in the range of 450°C to 700°C. C: 0.08% to 0.20%, Si: 0.40% or less, Mn: 0.5% to 5.0%, P: 0.010% or less, S: 0.0050% or less, Cr: 3.0% or less, Ni: 0.1% to 5.0%, Al: 0.010% to 0.080%, N: 0.0070% or less, and O: 0.0025% or less, Cu: 0.50% or less, Mo: 1.50% or less, V: 0.400% or less, Nb: 0.100% or less, Ti: 0.005% to 0.020%, Mg: 0.0001% to 0.0050%, Ta: 0.01% to 0.20%, Zr: 0.005% to 0.1%, Y: 0.001% to 0.01%, B: 0.0030% or less, Ca: 0.0005% to 0.0050%, and REM: 0.0005% to 0.0100%, heating steel to 1200°C to 1350°C, hot-forging the steel at a cumulative reduction of 25% or more, heating the steel to an Ac3 temperature or more and 1200°C or less, hot-rolling the steel at a cumulative rolling reduction of 40% or more, leaving the steel to cool, reheating the steel to the Ac3 temperature or more and 1050°C or less, rapidly cooling the steel from the Ac3 temperature or more to a lower temperature, which is both 350°C or less and an Ar3 temperature or less, and tempering the steel at a temperature in the range of 450°C to 700°C.