A steel for mold, consisting of: 0.50 mass% ≤ C ≤ 0.65 mass%, 0.01 mass% ≤ Si ≤ 0.30 mass%, 1.5 mass% ≤ Mn ≤ 3.0 mass%, 0.5 mass% ≤ Cr ≤ 1.4 mass%, 1.9 mass% ≤ Mo+W/2 ≤ 4.0 mass%, 0.2 mass% ≤ V ≤ 1.0 mass%, 0.01 ≤ N ≤ 0.10 mass%, and optionally, Al ≤ 1.5 mass%, Ti ≤ 0.5 mass%, Nb ≤ 0.5 mass%, Zr ≤ 0.5 mass%, Ta ≤ 0.5 mass%, Co ≤ 1.0 mass%, Ni ≤ 1.0 mass%, Cu ≤ 1.0 mass%, S ≤ 0.15 mass%, Ca ≤ 0.15 mass%, Se ≤ 0.35 mass%, Te ≤ 0.35 mass%, Bi ≤ 0.50 mass%, and Pb ≤ 0.50 mass%, with the balance being Fe and inevitable impurities, wherein, in a state after a) soaking at 1030°C±20°C for 45 min±15 min and then quenching at a cooling rate of 9°C/min to 30°C/min, and b) performing twice tempering of soaking at 540°C to 600°C for 1 hour and then air-cooling, the steel comprises: a carbide containing Mo and/or W having an equivalent circle diameter of 0.2 μm or less being in an amount of 1.2 mass% or more, wherein the total amount of carbides was measured by electrolytic extraction, and the extracted carbides were analyzed by SEM-EDX, a mass ratio of the amount of the carbide containing Mo and/or W having a diameter of 0.2 μm or less to an amount of a Cr carbide having a diameter of 0.2 μm or less being 11 or more, and a hardness change of 15 HRC or less, wherein the hardness change is |H b -H a |, wherein H a represents the Rockwell Hardness, C scale, measured at room temperature after quenching and tempering under the above-described conditions and further holding at 600°C for 130 hours, and H b is the Rockwell hardness, C scale, measured at room temperature immediately after quenching and tempering under the above-described conditions. 0.50 mass% ≤ C ≤ 0.65 mass%, 0.01 mass% ≤ Si ≤ 0.30 mass%, 1.5 mass% ≤ Mn ≤ 3.0 mass%, 0.5 mass% ≤ Cr ≤ 1.4 mass%, 1.9 mass% ≤ Mo+W/2 ≤ 4.0 mass%, 0.2 mass% ≤ V ≤ 1.0 mass%, 0.01 ≤ N ≤ 0.10 mass%, and optionally, Al ≤ 1.5 mass%, Ti ≤ 0.5 mass%, Nb ≤ 0.5 mass%, Zr ≤ 0.5 mass%, Ta ≤ 0.5 mass%, Co ≤ 1.0 mass%, Ni ≤ 1.0 mass%, Cu ≤ 1.0 mass%, S ≤ 0.15 mass%, Ca ≤ 0.15 mass%, Se ≤ 0.35 mass%, Te ≤ 0.35 mass%, Bi ≤ 0.50 mass%, and Pb ≤ 0.50 mass%, Al ≤ 1.5 mass%, Ti ≤ 0.5 mass%, Nb ≤ 0.5 mass%, Zr ≤ 0.5 mass%, Ta ≤ 0.5 mass%, Co ≤ 1.0 mass%, Ni ≤ 1.0 mass%, Cu ≤ 1.0 mass%, S ≤ 0.15 mass%, Ca ≤ 0.15 mass%, Se ≤ 0.35 mass%, Te ≤ 0.35 mass%, Bi ≤ 0.50 mass%, and Pb ≤ 0.50 mass%, with the balance being Fe and inevitable impurities, wherein, in a state after a) soaking at 1030°C±20°C for 45 min±15 min and then quenching at a cooling rate of 9°C/min to 30°C/min, and b) performing twice tempering of soaking at 540°C to 600°C for 1 hour and then air-cooling, the steel comprises: a carbide containing Mo and/or W having an equivalent circle diameter of 0.2 μm or less being in an amount of 1.2 mass% or more, wherein the total amount of carbides was measured by electrolytic extraction, and the extracted carbides were analyzed by SEM-EDX, a mass ratio of the amount of the carbide containing Mo and/or W having a diameter of 0.2 μm or less to an amount of a Cr carbide having a diameter of 0.2 μm or less being 11 or more, and a hardness change of 15 HRC or less, wherein the hardness change is |H b -H a |, wherein H a represents the Rockwell Hardness, C scale, measured at room temperature after quenching and tempering under the above-described conditions and further holding at 600°C for 130 hours, and H b is the Rockwell hardness, C scale, measured at room temperature immediately after quenching and tempering under the above-described conditions. a carbide containing Mo and/or W having an equivalent circle diameter of 0.2 μm or less being in an amount of 1.2 mass% or more, wherein the total amount of carbides was measured by electrolytic extraction, and the extracted carbides were analyzed by SEM-EDX, a mass ratio of the amount of the carbide containing Mo and/or W having a diameter of 0.2 μm or less to an amount of a Cr carbide having a diameter of 0.2 μm or less being 11 or more, and a hardness change of 15 HRC or less, wherein the hardness change is |H b -H a |, wherein H a represents the Rockwell Hardness, C scale, measured at room temperature after quenching and tempering under the above-described conditions and further holding at 600°C for 130 hours, and H b is the Rockwell hardness, C scale, measured at room temperature immediately after quenching and tempering under the above-described conditions.