The -olefin-aromatic vinyl compound copolymer of the present invention is obtained by using a transition metal compound represented by the following Formula (1) and a promoter component to carry out copolymerization, and it is a novel -olefin-aromatic vinyl compound copolymer having a low alternating property and a high blocking property, particularly a high blocking property related to the aromatic vinyl compound: ##STR1##

wherein A¹ and A² represent a cyclopentadienyl group, a substituted cyclopentadienyl group or the like; Y¹ and Y² represent a substituted or unsubstituted alkylene group or the like, and at least one of them is the substituted or unsubstituted alkylene group; M¹ represents titanium or the like; X¹ and X² represent a hydrogen atom, a halogen atom or the like.