A separator for a non-aqueous secondary battery, the separator comprising: a porous substrate; and an adhesive porous layer that is provided on one side or both sides of the porous substrate and contains the following resin A and resin B1, wherein a molecular weight distribution (Mw/Mn), which is a ratio of a weight-average molecular weight (Mw) to a number-average molecular weight (Mn), of an entirety of the resin A and the resin B1 is more than 2.0; wherein the molecular weight distribution (Mw/Mn), the weight-average molecular weight (Mw) and the number-average molecular weight (Mn) are determined using the methods provided in the description: resin A: a polyvinylidene fluoride type resin that is a copolymer containing, as monomer components, vinylidene fluoride and hexafluoropropylene, wherein a molar content of a hexafluoropropylene monomer unit with respect to a total molar quantity of a vinylidene fluoride monomer unit and the hexafluoropropylene monomer unit is from more than 1.5 mol% to 3.5 mol%, and resin B1: a polyvinylidene fluoride type resin that is a copolymer containing, as monomer components, vinylidene fluoride, hexafluoropropylene, and a monomer represented by the following formula, wherein a molar content of a hexafluoropropylene monomer unit with respect to a total molar quantity of a vinylidene fluoride monomer unit, the hexafluoropropylene monomer unit, and a monomer unit represented by the following formula is from more than 3.5 mol% to 15 mol%: wherein, in Formula, each of R 1, R 2, and R 3 independently represents a hydrogen atom, a halogen atom, a carboxyl group or a derivative thereof, or a C 1-5 alkyl group; X represents a single bond, a C 1-5 alkylene group, or a substituted C 1-5 alkylene group; and Y represents a hydrogen atom. a porous substrate; and an adhesive porous layer that is provided on one side or both sides of the porous substrate and contains the following resin A and resin B1, wherein a molecular weight distribution (Mw/Mn), which is a ratio of a weight-average molecular weight (Mw) to a number-average molecular weight (Mn), of an entirety of the resin A and the resin B1 is more than 2.0; wherein the molecular weight distribution (Mw/Mn), the weight-average molecular weight (Mw) and the number-average molecular weight (Mn) are determined using the methods provided in the description: resin A: a polyvinylidene fluoride type resin that is a copolymer containing, as monomer components, vinylidene fluoride and hexafluoropropylene, wherein a molar content of a hexafluoropropylene monomer unit with respect to a total molar quantity of a vinylidene fluoride monomer unit and the hexafluoropropylene monomer unit is from more than 1.5 mol% to 3.5 mol%, and resin B1: a polyvinylidene fluoride type resin that is a copolymer containing, as monomer components, vinylidene fluoride, hexafluoropropylene, and a monomer represented by the following formula, wherein a molar content of a hexafluoropropylene monomer unit with respect to a total molar quantity of a vinylidene fluoride monomer unit, the hexafluoropropylene monomer unit, and a monomer unit represented by the following formula is from more than 3.5 mol% to 15 mol%: resin A: a polyvinylidene fluoride type resin that is a copolymer containing, as monomer components, vinylidene fluoride and hexafluoropropylene, wherein a molar content of a hexafluoropropylene monomer unit with respect to a total molar quantity of a vinylidene fluoride monomer unit and the hexafluoropropylene monomer unit is from more than 1.5 mol% to 3.5 mol%, and resin B1: a polyvinylidene fluoride type resin that is a copolymer containing, as monomer components, vinylidene fluoride, hexafluoropropylene, and a monomer represented by the following formula, wherein a molar content of a hexafluoropropylene monomer unit with respect to a total molar quantity of a vinylidene fluoride monomer unit, the hexafluoropropylene monomer unit, and a monomer unit represented by the following formula is from more than 3.5 mol% to 15 mol%: wherein, in Formula, each of R 1, R 2, and R 3 independently represents a hydrogen atom, a halogen atom, a carboxyl group or a derivative thereof, or a C 1-5 alkyl group; X represents a single bond, a C 1-5 alkylene group, or a substituted C 1-5 alkylene group; and Y represents a hydrogen atom.