A method for preparing an olefin-diene copolymer, comprising: polymerizing at least one olefin-based monomer and at least one diene-based monomer in the presence of a catalyst comprising a transition metal compound represented by the following formula 1: wherein M is a Group 4 transition metal; Q 1 and Q 2 are independently a halogen, C 1 -C 20 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl, C 6 -C 20 aryl, C 1 -C 20 alkyl C 6 -C 20 aryl, C 6 -C 20 aryl C 1 -C 20 alkyl, C 1 -C 20 alkylamido, or C 6 -C 20 arylamido; R 1, R 2, R 3, R 4, R 5, R 6, R 7, R 8, R 7, and R 10 are independently hydrogen; C 1 -C 20 alkyl with or without an acetal, ketal, or ether group; C 2 -C 20 alkenyl with or without an acetal, ketal, or ether group; C 1 -C 20 alkyl C 6 -C 20 aryl with or without an acetal, ketal, or ether group; C 6 -C 20 aryl C 1 -C 20 alkyl with or without an acetal, ketal, or ether group; or C 1 -C 20 silyl with or without an acetal, ketal, or ether group; and R 11, R 12, and R 13 are independently hydrogen; C 1 -C 20 alkyl with or without an acetal, ketal, or ether group; C 2 -C 20 alkenyl with or without an acetal, ketal, or ether group; C 1 -C 20 alkyl C 6 -C 20 aryl with or without an acetal, ketal, or ether group; C 6 -C 20 aryl C 1 -C 20 alkyl with or without an acetal, ketal, or ether group; C 1 -C 20 silyl with or without an acetal, ketal, or ether group; C 1 -C 20 alkoxy; or C 6 -C 20 aryloxy. polymerizing at least one olefin-based monomer and at least one diene-based monomer in the presence of a catalyst comprising a transition metal compound represented by the following formula 1: wherein M is a Group 4 transition metal; Q 1 and Q 2 are independently a halogen, C 1 -C 20 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl, C 6 -C 20 aryl, C 1 -C 20 alkyl C 6 -C 20 aryl, C 6 -C 20 aryl C 1 -C 20 alkyl, C 1 -C 20 alkylamido, or C 6 -C 20 arylamido; R 1, R 2, R 3, R 4, R 5, R 6, R 7, R 8, R 7, and R 10 are independently hydrogen; C 1 -C 20 alkyl with or without an acetal, ketal, or ether group; C 2 -C 20 alkenyl with or without an acetal, ketal, or ether group; C 1 -C 20 alkyl C 6 -C 20 aryl with or without an acetal, ketal, or ether group; C 6 -C 20 aryl C 1 -C 20 alkyl with or without an acetal, ketal, or ether group; or C 1 -C 20 silyl with or without an acetal, ketal, or ether group; and R 11, R 12, and R 13 are independently hydrogen; C 1 -C 20 alkyl with or without an acetal, ketal, or ether group; C 2 -C 20 alkenyl with or without an acetal, ketal, or ether group; C 1 -C 20 alkyl C 6 -C 20 aryl with or without an acetal, ketal, or ether group; C 6 -C 20 aryl C 1 -C 20 alkyl with or without an acetal, ketal, or ether group; C 1 -C 20 silyl with or without an acetal, ketal, or ether group; C 1 -C 20 alkoxy; or C 6 -C 20 aryloxy. wherein M is a Group 4 transition metal; Q 1 and Q 2 are independently a halogen, C 1 -C 20 alkyl, C 2 -C 20 alkenyl, C 2 -C 20 alkynyl, C 6 -C 20 aryl, C 1 -C 20 alkyl C 6 -C 20 aryl, C 6 -C 20 aryl C 1 -C 20 alkyl, C 1 -C 20 alkylamido, or C 6 -C 20 arylamido; R 1, R 2, R 3, R 4, R 5, R 6, R 7, R 8, R 7, and R 10 are independently hydrogen; C 1 -C 20 alkyl with or without an acetal, ketal, or ether group; C 2 -C 20 alkenyl with or without an acetal, ketal, or ether group; C 1 -C 20 alkyl C 6 -C 20 aryl with or without an acetal, ketal, or ether group; C 6 -C 20 aryl C 1 -C 20 alkyl with or without an acetal, ketal, or ether group; or C 1 -C 20 silyl with or without an acetal, ketal, or ether group; and R 11, R 12, and R 13 are independently hydrogen; C 1 -C 20 alkyl with or without an acetal, ketal, or ether group; C 2 -C 20 alkenyl with or without an acetal, ketal, or ether group; C 1 -C 20 alkyl C 6 -C 20 aryl with or without an acetal, ketal, or ether group; C 6 -C 20 aryl C 1 -C 20 alkyl with or without an acetal, ketal, or ether group; C 1 -C 20 silyl with or without an acetal, ketal, or ether group; C 1 -C 20 alkoxy; or C 6 -C 20 aryloxy.