An object of the present disclosure is to provide a copolymer containing at least an acyclic non-conjugated olefin unit and a conjugated diene unit and capable of improving an elastic modulus of a rubber composition. Specifically, the present disclosure provides a copolymer containing at least an acyclic non-conjugated olefin unit and a conjugated diene unit, wherein the difference (Tem−Tim) between an extrapolated melting end temperature (Tem) as measured in accordance with JIS K7121 and an extrapolated melting initiation temperature (Tim) as measured in accordance with JIS K7121 is not higher than 60° C.