A method of manufacturing a hot pressed member, the method comprising: heating a slab and hot rolling the slab to obtain a hot rolled steel sheet, the slab having a chemical composition consisting of, in mass%, C: 0.090 % or more and less than 0.30 %, Mn: 3.5 % or more and less than 11.0 %, Si: 0.01 % to 2.5 %, P: 0.05 % or less, S: 0.05 % or less, Al: 0.005 % to 0.1 %, N: 0.01 % or less, optionally one or more groups selected from A group: one or more selected from Ni: 0.01 % to 5.0 %, Cu: 0.01 % to 5.0 %, Cr: 0.01 % to 5.0 %, and Mo: 0.01 % to 3.0 %, B group: one or more selected from Ti: 0.005 % to 3.0 %, Nb: 0.005 % to 3.0 %, V: 0.005 % to 3.0 %, and W: 0.005 % to 3.0 %, C group: one or more selected from REM: 0.0005 % to 0.01 %, Ca: 0.0005 % to 0.01 %, and Mg: 0.0005 % to 0.01 %, D group: Sb: 0.002 % to 0.03 %, and E group: B: 0.0005 % to 0.05 %, with a balance being Fe and incidental impurities including O, oxygen, 0.0100 % or less; heating the hot rolled steel sheet to a first temperature that is an Ac1 point or more and an Ac3 point or less, retaining the hot rolled steel sheet at the first temperature for 1 hr or more and 48 hr or less, and then cooling the hot rolled steel sheet to obtain a first blank steel sheet; cold rolling the first blank steel sheet to obtain a cold rolled steel sheet and annealing the cold rolled steel sheet to obtain a second blank steel sheet, the annealing including heating the cold rolled steel sheet to a temperature that is the Ac1 point or more and the Ac3 point or less, retaining the cold rolled steel sheet at the temperature for 30 seconds or more and 300 seconds or less, and then cooling the cold rolled steel sheet, performing a heating process of heating the second blank steel sheet to a second temperature that is the Ac3 point or more and 1000 °C or less and retaining the second blank steel sheet at the second temperature for 900 sec or less; and thereafter performing a hot press forming process of simultaneously press forming and quenching the second blank steel sheet using a press tool for forming, to obtain a hot pressed member, where Ac1 point, °C, and Ac3 point, °C, are calculated according to the following expressions: Ac 1 point, ° C = 751 − 16 ⁢ C + 11 ⁢ Si − 28 ⁢ Mn − 5.5 ⁢ Cu − 16 ⁢ Ni + 13 ⁢ Cr + 3.4 ⁢ Mo Ac 3 point, ° C = 910 − 203 C 1 / 2 + 44.7 ⁢ Si − 4 ⁢ Mn + 11 ⁢ Cr where C, Si, Mn, Ni, Cu, Cr, and Mo are each the content in mass% of the corresponding element, in the case where the element is not contained, the content of the element is assumed to be 0. heating a slab and hot rolling the slab to obtain a hot rolled steel sheet, the slab having a chemical composition consisting of, in mass%, C: 0.090 % or more and less than 0.30 %, Mn: 3.5 % or more and less than 11.0 %, Si: 0.01 % to 2.5 %, P: 0.05 % or less, S: 0.05 % or less, Al: 0.005 % to 0.1 %, N: 0.01 % or less, C: 0.090 % or more and less than 0.30 %, Mn: 3.5 % or more and less than 11.0 %, Si: 0.01 % to 2.5 %, P: 0.05 % or less, S: 0.05 % or less, Al: 0.005 % to 0.1 %, N: 0.01 % or less, optionally one or more groups selected from A group: one or more selected from Ni: 0.01 % to 5.0 %, Cu: 0.01 % to 5.0 %, Cr: 0.01 % to 5.0 %, and Mo: 0.01 % to 3.0 %, B group: one or more selected from Ti: 0.005 % to 3.0 %, Nb: 0.005 % to 3.0 %, V: 0.005 % to 3.0 %, and W: 0.005 % to 3.0 %, C group: one or more selected from REM: 0.0005 % to 0.01 %, Ca: 0.0005 % to 0.01 %, and Mg: 0.0005 % to 0.01 %, D group: Sb: 0.002 % to 0.03 %, and E group: B: 0.0005 % to 0.05 %, A group: one or more selected from Ni: 0.01 % to 5.0 %, Cu: 0.01 % to 5.0 %, Cr: 0.01 % to 5.0 %, and Mo: 0.01 % to 3.0 %, B group: one or more selected from Ti: 0.005 % to 3.0 %, Nb: 0.005 % to 3.0 %, V: 0.005 % to 3.0 %, and W: 0.005 % to 3.0 %, C group: one or more selected from REM: 0.0005 % to 0.01 %, Ca: 0.0005 % to 0.01 %, and Mg: 0.0005 % to 0.01 %, D group: Sb: 0.002 % to 0.03 %, and E group: B: 0.0005 % to 0.05 %, with a balance being Fe and incidental impurities including O, oxygen, 0.0100 % or less; heating the hot rolled steel sheet to a first temperature that is an Ac1 point or more and an Ac3 point or less, retaining the hot rolled steel sheet at the first temperature for 1 hr or more and 48 hr or less, and then cooling the hot rolled steel sheet to obtain a first blank steel sheet; cold rolling the first blank steel sheet to obtain a cold rolled steel sheet and annealing the cold rolled steel sheet to obtain a second blank steel sheet, the annealing including heating the cold rolled steel sheet to a temperature that is the Ac1 point or more and the Ac3 point or less, retaining the cold rolled steel sheet at the temperature for 30 seconds or more and 300 seconds or less, and then cooling the cold rolled steel sheet, performing a heating process of heating the second blank steel sheet to a second temperature that is the Ac3 point or more and 1000 °C or less and retaining the second blank steel sheet at the second temperature for 900 sec or less; and thereafter performing a hot press forming process of simultaneously press forming and quenching the second blank steel sheet using a press tool for forming, to obtain a hot pressed member, where Ac1 point, °C, and Ac3 point, °C, are calculated according to the following expressions: Ac 1 point, ° C = 751 − 16 ⁢ C + 11 ⁢ Si − 28 ⁢ Mn − 5.5 ⁢ Cu − 16 ⁢ Ni + 13 ⁢ Cr + 3.4 ⁢ Mo Ac 3 point, ° C = 910 − 203 C 1 / 2 + 44.7 ⁢ Si − 4 ⁢ Mn + 11 ⁢ Cr where C, Si, Mn, Ni, Cu, Cr, and Mo are each the content in mass% of the corresponding element, in the case where the element is not contained, the content of the element is assumed to be 0.