A method for producing heterophasic propylene polymerization material particles, the method comprising: performing monomer polymerization in the presence of a catalyst including a solid catalyst component so as to obtain a component recited below; performing monomer polymerization in the presence of the component so as to obtain a component, so that particles including a volatile component, the component, and the component are produced; and causing the particles to contact with an inert gas-containing stream so as to remove the volatile component from the particles, the particles including the component by 20 to 70 mass%, and the component by 30 to 80 mass%, and the method satisfying Inequation: 19.5 ≤ T 1.12 ⋅ t 0.17 ⋅ C / 100 0.61 / d ⋅ 0.85 ⋅ P 1 / 3 0.13 ≤ 51.4 where T [°C] is a temperature that the particles have when the particles contact with the inert gas-containing stream, t [h] is a contact time period in which the particles contact with the inert gas-containing stream, d [μm] is a median diameter that the solid catalyst component has at the time of start of step, P [g/g] is a mass of the particles per 1 g of the solid catalyst component, and C [mass%] is the content of the component in the particles, the component including a component (I-1) and/or a component, the component (I-1) being a propylene homopolymer, the component being a propylene copolymer including a propylene-derived structural unit and at least one type of olefin-derived structural unit selected from the group consisting of ethylene and C4 to C12 α-olefins, wherein a mass ratio of the at least one type of olefin-derived structural unit in the mass of the copolymer is less than 15 mass%, and the component being a propylene copolymer including a propylene-derived structural unit and at least one type of olefin-derived structural unit selected from the group consisting of ethylene and C4 to C12 α-olefins, wherein a mass ratio of the at least one type of olefin-derived structural unit in the mass of the copolymer is in a range of 15 to 80 mass%. performing monomer polymerization in the presence of a catalyst including a solid catalyst component so as to obtain a component recited below; performing monomer polymerization in the presence of the component so as to obtain a component, so that particles including a volatile component, the component, and the component are produced; and causing the particles to contact with an inert gas-containing stream so as to remove the volatile component from the particles, the particles including the component by 20 to 70 mass%, and the component by 30 to 80 mass%, and the method satisfying Inequation: 19.5 ≤ T 1.12 ⋅ t 0.17 ⋅ C / 100 0.61 / d ⋅ 0.85 ⋅ P 1 / 3 0.13 ≤ 51.4 where T [°C] is a temperature that the particles have when the particles contact with the inert gas-containing stream, t [h] is a contact time period in which the particles contact with the inert gas-containing stream, d [μm] is a median diameter that the solid catalyst component has at the time of start of step, P [g/g] is a mass of the particles per 1 g of the solid catalyst component, and C [mass%] is the content of the component in the particles, the component including a component (I-1) and/or a component, the component (I-1) being a propylene homopolymer, the component being a propylene copolymer including a propylene-derived structural unit and at least one type of olefin-derived structural unit selected from the group consisting of ethylene and C4 to C12 α-olefins, wherein a mass ratio of the at least one type of olefin-derived structural unit in the mass of the copolymer is less than 15 mass%, and the component being a propylene copolymer including a propylene-derived structural unit and at least one type of olefin-derived structural unit selected from the group consisting of ethylene and C4 to C12 α-olefins, wherein a mass ratio of the at least one type of olefin-derived structural unit in the mass of the copolymer is in a range of 15 to 80 mass%. the particles including the component by 20 to 70 mass%, and the component by 30 to 80 mass%, and the method satisfying Inequation: 19.5 ≤ T 1.12 ⋅ t 0.17 ⋅ C / 100 0.61 / d ⋅ 0.85 ⋅ P 1 / 3 0.13 ≤ 51.4 where T [°C] is a temperature that the particles have when the particles contact with the inert gas-containing stream, t [h] is a contact time period in which the particles contact with the inert gas-containing stream, d [μm] is a median diameter that the solid catalyst component has at the time of start of step, P [g/g] is a mass of the particles per 1 g of the solid catalyst component, and C [mass%] is the content of the component in the particles, the component including a component (I-1) and/or a component, the component (I-1) being a propylene homopolymer, the component being a propylene copolymer including a propylene-derived structural unit and at least one type of olefin-derived structural unit selected from the group consisting of ethylene and C4 to C12 α-olefins, wherein a mass ratio of the at least one type of olefin-derived structural unit in the mass of the copolymer is less than 15 mass%, and the component being a propylene copolymer including a propylene-derived structural unit and at least one type of olefin-derived structural unit selected from the group consisting of ethylene and C4 to C12 α-olefins, wherein a mass ratio of the at least one type of olefin-derived structural unit in the mass of the copolymer is in a range of 15 to 80 mass%.