A high-strength steel sheet with a tensile strength of 590 MPa or more measured in accordance with JIS Z 2241 as defined in the description, the high-strength steel sheet comprising a chemical composition comprising: by mass%, C in a range from 0.05 to 0.30%; Si of 2.50% or less; Mn in a range from 0.50 to 3.50%; P of 0.100% or less; S of 0.0100% or less; Al in a range from 0.001 to 2.000%; N of 0.0150% or less; O of 0.0050% or less; and optionally, H, Na, Cl, Sc, Co, Zn, Ga, Ge, As, Se, Y, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, Cs, Ta, Re, Os, Ir, Pt, Au and Pb at 0.010% or less in total, the balance consisting of Fe and inevitable impurities, wherein the chemical composition optionally further comprises, by mass%, in place of a part of Fe: one or more of Ti of 0.30% or less, Nb of 0.10% or less, and V of 1.00% or less; one or more of Cr of 2.00% or less, Ni of 2.00% or less, Cu of 2.00% or less, Mo of 1.00% or less, W of 1.00% or less, B of 0.0100% or less, Sn of 1.00% or less, and Sb of 0.20% or less; and/or one or more of Ca, Ce, Mg, Zr, La, Hf, and REM at 0.0100% or less in total, the high-strength steel sheet comprising a microstructure in a region from 1/8t to 3/8t from a steel sheet surface, wherein t is the sheet thickness, the microstructure comprising: by volume%, acicular ferrite of 20% or more; martensite of 10% or more; aggregated ferrite of 20% or less; residual austenite of 2.0% or less; and 5% or less of a structure other than a structure comprising bainite and bainitic ferrite in addition to the above whole structure, wherein the martensite satisfies a formula below, ∑ i = 1 5 d i a i 1.5 ≤ 10.0 where: d i represents a circle-equivalent diameter in μm of the i-th largest island-shaped martensite in the microstructure in the region of 1/8t to 3/8t, and a i represents an aspect ratio of the i-th largest island-shaped martensite in the microstructure in the region of 1/8t to 3/8t. C in a range from 0.05 to 0.30%; Si of 2.50% or less; Mn in a range from 0.50 to 3.50%; P of 0.100% or less; S of 0.0100% or less; Al in a range from 0.001 to 2.000%; N of 0.0150% or less; O of 0.0050% or less; and optionally, H, Na, Cl, Sc, Co, Zn, Ga, Ge, As, Se, Y, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, Cs, Ta, Re, Os, Ir, Pt, Au and Pb at 0.010% or less in total, the balance consisting of Fe and inevitable impurities, wherein the chemical composition optionally further comprises, by mass%, in place of a part of Fe: one or more of Ti of 0.30% or less, Nb of 0.10% or less, and V of 1.00% or less; one or more of Cr of 2.00% or less, Ni of 2.00% or less, Cu of 2.00% or less, Mo of 1.00% or less, W of 1.00% or less, B of 0.0100% or less, Sn of 1.00% or less, and Sb of 0.20% or less; and/or one or more of Ca, Ce, Mg, Zr, La, Hf, and REM at 0.0100% or less in total, the high-strength steel sheet comprising a microstructure in a region from 1/8t to 3/8t from a steel sheet surface, wherein t is the sheet thickness, the microstructure comprising: by volume%, acicular ferrite of 20% or more; martensite of 10% or more; aggregated ferrite of 20% or less; residual austenite of 2.0% or less; and 5% or less of a structure other than a structure comprising bainite and bainitic ferrite in addition to the above whole structure, wherein the martensite satisfies a formula below, ∑ i = 1 5 d i a i 1.5 ≤ 10.0 where: d i represents a circle-equivalent diameter in μm of the i-th largest island-shaped martensite in the microstructure in the region of 1/8t to 3/8t, and a i represents an aspect ratio of the i-th largest island-shaped martensite in the microstructure in the region of 1/8t to 3/8t. one or more of Ti of 0.30% or less, Nb of 0.10% or less, and V of 1.00% or less; one or more of Cr of 2.00% or less, Ni of 2.00% or less, Cu of 2.00% or less, Mo of 1.00% or less, W of 1.00% or less, B of 0.0100% or less, Sn of 1.00% or less, and Sb of 0.20% or less; and/or one or more of Ca, Ce, Mg, Zr, La, Hf, and REM at 0.0100% or less in total, the high-strength steel sheet comprising a microstructure in a region from 1/8t to 3/8t from a steel sheet surface, wherein t is the sheet thickness, the microstructure comprising: by volume%, acicular ferrite of 20% or more; martensite of 10% or more; aggregated ferrite of 20% or less; residual austenite of 2.0% or less; and 5% or less of a structure other than a structure comprising bainite and bainitic ferrite in addition to the above whole structure, wherein the martensite satisfies a formula below, ∑ i = 1 5 d i a i 1.5 ≤ 10.0 where: d i represents a circle-equivalent diameter in μm of the i-th largest island-shaped martensite in the microstructure in the region of 1/8t to 3/8t, and a i represents an aspect ratio of the i-th largest island-shaped martensite in the microstructure in the region of 1/8t to 3/8t.