A curable composition, comprising: an olefin-aromatic vinyl compound-aromatic polyene copolymerized oligomer satisfying the following conditions to: a number average molecular weight of the oligomer is 500 or more and less than 5000, as measured by a gel permeation chromatography using standard polystyrene; the aromatic vinyl compound monomer is an aromatic vinyl compound having 8 or more and 20 or less carbon atoms, and a content of the aromatic vinyl compound monomer unit is more than 0 mass% and 70 mass% or less; the aromatic polyene monomer is one or more selected from polyenes having 5 or more and 20 or less carbon atoms and having a plurality of vinyl groups and/or vinylene groups in the molecule, and a content of the vinyl groups and/or the vinylene groups derived from the aromatic polyene is 1.5 pieces or more and less than 20 pieces per number average molecular weight; and the olefin monomer is one or more selected from olefins having 2 or more and 20 or less carbon atoms, and a content of the olefin monomer unit is 30 mass% or more, wherein a total of the olefin monomer unit, the aromatic vinyl compound monomer unit, and the aromatic polyene monomer unit is 100 mass%; and an olefin-aromatic vinyl compound-aromatic polyene copolymer satisfying the following conditions to: a number average molecular weight of the copolymer is 5000 or more and 100000 or less, as measured by a gel permeation chromatography using standard polystyrene; the aromatic vinyl compound monomer is an aromatic vinyl compound having 8 or more and 20 or less carbon atoms, and a content of the aromatic vinyl compound monomer unit is more than 0 mass% and 70 mass% or less; the aromatic polyene is one or more selected from polyenes having 5 or more and 20 or less carbon atoms and having a plurality of vinyl groups and/or vinylene groups in the molecule, and a content of the vinyl groups and/or the vinylene groups derived from a unit of the aromatic polyene is 1.5 pieces or more and less than 20 pieces per number average molecular weight; and the olefin is one or more selected from olefins having 2 or more and 20 or less carbon atoms, and a total of units of the olefin monomer, the aromatic vinyl compound, and the aromatic polyene monomer is 100 mass%. a number average molecular weight of the oligomer is 500 or more and less than 5000, as measured by a gel permeation chromatography using standard polystyrene; the aromatic vinyl compound monomer is an aromatic vinyl compound having 8 or more and 20 or less carbon atoms, and a content of the aromatic vinyl compound monomer unit is more than 0 mass% and 70 mass% or less; the aromatic polyene monomer is one or more selected from polyenes having 5 or more and 20 or less carbon atoms and having a plurality of vinyl groups and/or vinylene groups in the molecule, and a content of the vinyl groups and/or the vinylene groups derived from the aromatic polyene is 1.5 pieces or more and less than 20 pieces per number average molecular weight; and the olefin monomer is one or more selected from olefins having 2 or more and 20 or less carbon atoms, and a content of the olefin monomer unit is 30 mass% or more, wherein a total of the olefin monomer unit, the aromatic vinyl compound monomer unit, and the aromatic polyene monomer unit is 100 mass%; and an olefin-aromatic vinyl compound-aromatic polyene copolymer satisfying the following conditions to: a number average molecular weight of the copolymer is 5000 or more and 100000 or less, as measured by a gel permeation chromatography using standard polystyrene; the aromatic vinyl compound monomer is an aromatic vinyl compound having 8 or more and 20 or less carbon atoms, and a content of the aromatic vinyl compound monomer unit is more than 0 mass% and 70 mass% or less; the aromatic polyene is one or more selected from polyenes having 5 or more and 20 or less carbon atoms and having a plurality of vinyl groups and/or vinylene groups in the molecule, and a content of the vinyl groups and/or the vinylene groups derived from a unit of the aromatic polyene is 1.5 pieces or more and less than 20 pieces per number average molecular weight; and the olefin is one or more selected from olefins having 2 or more and 20 or less carbon atoms, and a total of units of the olefin monomer, the aromatic vinyl compound, and the aromatic polyene monomer is 100 mass%. a number average molecular weight of the copolymer is 5000 or more and 100000 or less, as measured by a gel permeation chromatography using standard polystyrene; the aromatic vinyl compound monomer is an aromatic vinyl compound having 8 or more and 20 or less carbon atoms, and a content of the aromatic vinyl compound monomer unit is more than 0 mass% and 70 mass% or less; the aromatic polyene is one or more selected from polyenes having 5 or more and 20 or less carbon atoms and having a plurality of vinyl groups and/or vinylene groups in the molecule, and a content of the vinyl groups and/or the vinylene groups derived from a unit of the aromatic polyene is 1.5 pieces or more and less than 20 pieces per number average molecular weight; and the olefin is one or more selected from olefins having 2 or more and 20 or less carbon atoms, and a total of units of the olefin monomer, the aromatic vinyl compound, and the aromatic polyene monomer is 100 mass%.