Alpha-olefin-aromatic vinyl copolymer

An α-olefin-aromatic vinyl compound copolymer comprising α-olefin and an aromatic vinyl compound, wherein the aromatic vinyl compound has a content of 0.1 to 90 mole %;

• the molecular weight distribution measured by a GPC method is 3.0 or less;
• in 13C-NMR measurement, a signal (Sβδ) based on an (aromatic vinyl compound-olefin-olefin) chain and a signal (Sββ) based on an (aromatic vinyl compound-olefin-aromatic vinyl compound) chain are present, and a signal (Tββ) based on a blocking (aromatic vinyl compound-aromatic vinyl compound-aromatic vinyl compound) chain in the aromatic vinyl compound and a signal (Sδδ) based on a blocking (olefin-olefin-olefin) chain in the olefin part are present;
• and an index (θ) showing a blocking property of the aromatic vinyl compound component which is represented by the following relational equation is 10 to 80 (%):
• θ=I(Tββ+Tβδ)/[I(Tδδ+Tγδ+Tββ+Tβδ)]×100
• wherein I(Tββ+Tβδ) represents the sum of the intensities of the signals Tββ and Tβδ in 13C-NMR measurement, provided that Tβδ represents a signal based on an (aromatic vinyl compound-aromatic vinyl compound-olefin) chain;
• and I(Tδδ+Tγδ+Tββ+Tβδ)represents the sum of the respective intensities of the signals Tδδ, Tγδ, Tββ and Tβδ based on all chains in which the aromatic vinyl compound participates among the chains of the above copolymer in 13C-NMR measurement, provided that Tδδ represents a signal based on an (olefin-aromatic vinyl compound-olefin) chain, and Tγδ represents a signal based on a heterogeneous bond of an (aromatic vinyl compound-aromatic vinyl compound-olefin-olefin) chain or a signal based on a heterogeneous bond of an (aromatic vinyl compound-olefin-aromatic vinyl compound-olefin) chain.