An abrasion-resistant steel plate having a surface hardness of 350 or more and 450 or less in terms of Brinell hardness (HBW 10/3000), the steel plate comprising: a chemical composition consisting of, by mass%, C: 0.100% or more and less than 0.175%, Si: 0.05% or more and 1.00% or less, Mn: 0.50% or more and 1.90% or less, P: less than 0.006%, S: 0.005% or less, Al: 0.005% or more and 0.100% or less, Cr: 0.10% or more and 1.00% or less, Nb: 0.005% or more and 0.024% or less, Ti: 0.005% or more and 0.050% or less, B: 0.0003% or more and 0.0030% or less, N: 0.0010% or more and 0.0080% or less, optionally at least one selected from the group consisting of Mo: 0.05% or more and 0.80% or less, V: 0.005% or more and 0.10% or less, Cu: 0.10% or more and 1.00% or less, and Ni: 0.10% or more and 2.00% or less, optionally at least one selected from the group consisting of Ca: 0.0005% or more and 0.0040% or less, Mg: 0.0005% or more and 0.0050% or less, and REM: 0.0005% or more and 0.0080% or less, and the balance being Fe and inevitable impurities, the chemical composition satisfying relational expression and relational expression, and a microstructure at positions located at 1/4 of the thickness and at 3/4 of the thickness including a martensite single phase microstructure having an average prior austenite grain diameter of 20 μm or more and 60 μm or less, or a mixed microstructure of martensite and bainite having an average prior austenite grain diameter of 20 μm or more and 60 μm or less and martensite-austenite constituent in bainite being less than 5% in terms of area ratio with respect to the whole microstructure: DIH = 33.85 × 0.1 × C 0.5 × 0.7 × Si + 1 × 3.33 × Mn + 1 × 0.35 × Cu + 1 × 0.36 × Ni + 1 × 2.16 × Cr + 1 × 3 × Mo + 1 × 1.75 × V + 1 ≥ 35 CES = 5.5 × C 4 / 3 + 75.5 × P + 0.90 × Mn + 0.12 × Ni + 0.53 × Mo ≤ 2.70 where in both relational expressions, atomic symbols of the alloying elements denote the contents (mass%) of the corresponding elements, and the contents of the elements which are not contained are defined as 0. a chemical composition consisting of, by mass%, C: 0.100% or more and less than 0.175%, Si: 0.05% or more and 1.00% or less, Mn: 0.50% or more and 1.90% or less, P: less than 0.006%, S: 0.005% or less, Al: 0.005% or more and 0.100% or less, Cr: 0.10% or more and 1.00% or less, Nb: 0.005% or more and 0.024% or less, Ti: 0.005% or more and 0.050% or less, B: 0.0003% or more and 0.0030% or less, N: 0.0010% or more and 0.0080% or less, optionally at least one selected from the group consisting of Mo: 0.05% or more and 0.80% or less, V: 0.005% or more and 0.10% or less, Cu: 0.10% or more and 1.00% or less, and Ni: 0.10% or more and 2.00% or less, optionally at least one selected from the group consisting of Ca: 0.0005% or more and 0.0040% or less, Mg: 0.0005% or more and 0.0050% or less, and REM: 0.0005% or more and 0.0080% or less, and the balance being Fe and inevitable impurities, the chemical composition satisfying relational expression and relational expression, and a microstructure at positions located at 1/4 of the thickness and at 3/4 of the thickness including a martensite single phase microstructure having an average prior austenite grain diameter of 20 μm or more and 60 μm or less, or a mixed microstructure of martensite and bainite having an average prior austenite grain diameter of 20 μm or more and 60 μm or less and martensite-austenite constituent in bainite being less than 5% in terms of area ratio with respect to the whole microstructure: DIH = 33.85 × 0.1 × C 0.5 × 0.7 × Si + 1 × 3.33 × Mn + 1 × 0.35 × Cu + 1 × 0.36 × Ni + 1 × 2.16 × Cr + 1 × 3 × Mo + 1 × 1.75 × V + 1 ≥ 35 CES = 5.5 × C 4 / 3 + 75.5 × P + 0.90 × Mn + 0.12 × Ni + 0.53 × Mo ≤ 2.70 where in both relational expressions, atomic symbols of the alloying elements denote the contents (mass%) of the corresponding elements, and the contents of the elements which are not contained are defined as 0.