A resistance spot welding method of joining parts to be welded that are two or more overlapping steel sheets, wherein a steel sheet whose Mn content is highest of the overlapping steel sheets has a chemical composition that satisfies 0.050 % ≤ C ≤ 0.250 %, 3.50 % ≤ Mn ≤ 12.00 %, 0.001 % ≤ Si ≤ 2.000 %, 0.001 % ≤ P ≤ 0.025 %, and 0.0001 % ≤ S ≤ 0.0020 %, the resistance spot welding method comprises performing main current passage and subsequent current passage, with a cooling time of 0.01 s or more being provided between the main current passage and the subsequent current passage, and Ip/I which is a ratio of a current value of the subsequent current passage to a current value of the main current passage satisfies, depending on a constant A defined by the Mn content and P content in the chemical composition, any of the following Formulas to in relation to Tp, T, and the constant A: when A ≤ 0.04, 0.41 + A × 1 + T / 1 + Tp ≤ Ip/I ≤ 2.04 − A × 1 + T / 1 + Tp when 0.04 < A ≤ 0.09, 0.402 + 1.2 × A × 1 + T / 1 + Tp ≤ Ip/I ≤ 2.08 − 2 × A × 1 + T / 1 + Tp and when 0.09 < A ≤ 0.155, 0.393 + 1.3 × A × 1 + T / 1 + Tp ≤ Ip/I ≤ 2.17 − 3 × A × 1 + T / 1 + Tp where I denotes the current value of the main current passage expressed in kA, Ip denotes the current value of the subsequent current passage expressed in kA, Tp denotes a welding time of the subsequent current passage expressed in s, T denotes the cooling time expressed in s, and the constant A is defined by any of the following Formulas to depending on the Mn content: when 3.5 % ≤ Mn ≤ 4.5 %, A = Mn + 1.5 / 200 + P when 4.5 % < Mn ≤ 7.5 %, A = Mn − 1.5 / 100 + P and when 7.5 % < Mn ≤ 12.0 %, A = Mn − 3.9 / 60 + P where Mn and P are respectively the Mn content and the P content in the chemical composition. wherein a steel sheet whose Mn content is highest of the overlapping steel sheets has a chemical composition that satisfies 0.050 % ≤ C ≤ 0.250 %, 3.50 % ≤ Mn ≤ 12.00 %, 0.001 % ≤ Si ≤ 2.000 %, 0.001 % ≤ P ≤ 0.025 %, and 0.0001 % ≤ S ≤ 0.0020 %, the resistance spot welding method comprises performing main current passage and subsequent current passage, with a cooling time of 0.01 s or more being provided between the main current passage and the subsequent current passage, and Ip/I which is a ratio of a current value of the subsequent current passage to a current value of the main current passage satisfies, depending on a constant A defined by the Mn content and P content in the chemical composition, any of the following Formulas to in relation to Tp, T, and the constant A: when A ≤ 0.04, 0.41 + A × 1 + T / 1 + Tp ≤ Ip/I ≤ 2.04 − A × 1 + T / 1 + Tp when 0.04 < A ≤ 0.09, 0.402 + 1.2 × A × 1 + T / 1 + Tp ≤ Ip/I ≤ 2.08 − 2 × A × 1 + T / 1 + Tp and when 0.09 < A ≤ 0.155, 0.393 + 1.3 × A × 1 + T / 1 + Tp ≤ Ip/I ≤ 2.17 − 3 × A × 1 + T / 1 + Tp where I denotes the current value of the main current passage expressed in kA, Ip denotes the current value of the subsequent current passage expressed in kA, Tp denotes a welding time of the subsequent current passage expressed in s, T denotes the cooling time expressed in s, and the constant A is defined by any of the following Formulas to depending on the Mn content: when 3.5 % ≤ Mn ≤ 4.5 %, A = Mn + 1.5 / 200 + P when 4.5 % < Mn ≤ 7.5 %, A = Mn − 1.5 / 100 + P and when 7.5 % < Mn ≤ 12.0 %, A = Mn − 3.9 / 60 + P where Mn and P are respectively the Mn content and the P content in the chemical composition. when A ≤ 0.04, 0.41 + A × 1 + T / 1 + Tp ≤ Ip/I ≤ 2.04 − A × 1 + T / 1 + Tp when 0.04 < A ≤ 0.09, 0.402 + 1.2 × A × 1 + T / 1 + Tp ≤ Ip/I ≤ 2.08 − 2 × A × 1 + T / 1 + Tp and when 0.09 < A ≤ 0.155, 0.393 + 1.3 × A × 1 + T / 1 + Tp ≤ Ip/I ≤ 2.17 − 3 × A × 1 + T / 1 + Tp where I denotes the current value of the main current passage expressed in kA, Ip denotes the current value of the subsequent current passage expressed in kA, Tp denotes a welding time of the subsequent current passage expressed in s, T denotes the cooling time expressed in s, and the constant A is defined by any of the following Formulas to depending on the Mn content: when 3.5 % ≤ Mn ≤ 4.5 %, A = Mn + 1.5 / 200 + P when 4.5 % < Mn ≤ 7.5 %, A = Mn − 1.5 / 100 + P and when 7.5 % < Mn ≤ 12.0 %, A = Mn − 3.9 / 60 + P where Mn and P are respectively the Mn content and the P content in the chemical composition. when 3.5 % ≤ Mn ≤ 4.5 %, A = Mn + 1.5 / 200 + P when 4.5 % < Mn ≤ 7.5 %, A = Mn − 1.5 / 100 + P and when 7.5 % < Mn ≤ 12.0 %, A = Mn − 3.9 / 60 + P where Mn and P are respectively the Mn content and the P content in the chemical composition.