A transition metal compound represented by Chemical Formula 1 below: In Chemical Formula 1, M is a Group 4 transition metal in the Periodic Table of Elements; n is an integer of 1 or 2, each R 1 may be the same or different when n is 2; R 1 is hydrogen, (C1-C50)alkyl, halo(C1-C50)alkyl, (C3-C50)cycloalkyl, (C6-C30)aryl, (C6-C30)aryl(C1-C50)alkyl, ((C1-C50)alkyl(C6-C30)aryl)(C1-C50)alkyl, -NR a R b, -SiR c R d R e, or 5- through 7- membered N-heterocycloalkyl containing at least one nitrogen atom; R 2 and R 3 each are independently hydrogen, (C1-C50)alkyl, (C1-C50)alkoxy, halo(C1-C50)alkyl, (C3-C50)cycloalkyl, (C6-C30)aryl, (C6-C30)aryloxy, (C1-C50)alkyl(C6-C30)aryloxy, (C6-C30)aryl(C1-C50)alkyl, ((C1-C50)alkyl(C6-C30)aryl) (C1-C50)alkyl, -NR a R b or -SiR c R d R e; R 4, R 5, R 10, R 11 and R 12 each are independently (C1-C50)alkyl, halo(C1-C50)alkyl, (C3-C50)cycloalkyl, (C6-C30)aryl, (C6-C30)aryl(C1-C50)alkyl, ((C1-C50)alkyl(C6-C30) aryl) (C1-C50)alkyl, -NR a R b, or -SiR c R d R e, and R 11 and R 12 may be linked via (C4-C7)alkylene to form a ring; R 6, R 7, R 8 and R 9 each are independently hydrogen, (C1-C50)alkyl, halo(C1-C50)alkyl, (C3-C50)cycloalkyl, (C1-C50)alkoxy, (C6-C30)aryl, (C6-C30)aryl(C1-C50)alkyl, ((C1-C50)alkyl(C6-C30)aryl)(C1-C50)alkyl, (C6-C30)aryloxy, (C1-C50)alkyl(C6-C30)aryloxy, N-carbazolyl, -NR a R b, or -SiR c R d R e, or may be linked to an adjacent substituent via (C1-C5)alkylene to form a ring, and at least one -CH 2 - of the alkylene may be substituted by a hetero atom selected from - 0-, -S-, and -NR'-, and the alkylene may be further substituted with (C1-C50)alkyl; aryl of R 1 to R 12 may be further substituted with at least one substituent selected from the group consisting of (C1-C50)alkyl, halo(C1-C50)alkyl, (C1-C50)alkoxy, (C6-C30)aryloxy, (C6-C30)aryl, (C1-C50)alkyl(C6-C30)aryl, and (C6-C30)aryl(C1-C50)alkyl; R' and R a to R e each are independently (C1-C50)alkyl or (C6-C30)aryl; and X 1 and X 2. each are independently halogen, (C1-C50)alkyl, (C2-C50)alkenyl, (C3-C50)cycloalkyl, (C6-C30)aryl, (C6-C30)aryl(C1-C50)alkyl, ((C1-C50)alkyl(C6-C30)aryl)(C1-C50)alkyl, (C1-C50)alkoxy, (C6-C30)aryloxy, (C1-C50)alkyl(C6-C30)aryloxy, (C1-C50)alkoxy(C6-C30)aryloxy, (C1-C50)alkylidene, or an anion or dianion ligand consisting of 60 or less atoms containing N, P, O, S, Si, and halogen, except hydrogen, provided that one of X 1 and X 2 is a dianion ligand, the other is ignored. In Chemical Formula 1, M is a Group 4 transition metal in the Periodic Table of Elements; n is an integer of 1 or 2, each R 1 may be the same or different when n is 2; R 1 is hydrogen, (C1-C50)alkyl, halo(C1-C50)alkyl, (C3-C50)cycloalkyl, (C6-C30)aryl, (C6-C30)aryl(C1-C50)alkyl, ((C1-C50)alkyl(C6-C30)aryl)(C1-C50)alkyl, -NR a R b, -SiR c R d R e, or 5- through 7- membered N-heterocycloalkyl containing at least one nitrogen atom; R 2 and R 3 each are independently hydrogen, (C1-C50)alkyl, (C1-C50)alkoxy, halo(C1-C50)alkyl, (C3-C50)cycloalkyl, (C6-C30)aryl, (C6-C30)aryloxy, (C1-C50)alkyl(C6-C30)aryloxy, (C6-C30)aryl(C1-C50)alkyl, ((C1-C50)alkyl(C6-C30)aryl) (C1-C50)alkyl, -NR a R b or -SiR c R d R e; R 4, R 5, R 10, R 11 and R 12 each are independently (C1-C50)alkyl, halo(C1-C50)alkyl, (C3-C50)cycloalkyl, (C6-C30)aryl, (C6-C30)aryl(C1-C50)alkyl, ((C1-C50)alkyl(C6-C30) aryl) (C1-C50)alkyl, -NR a R b, or -SiR c R d R e, and R 11 and R 12 may be linked via (C4-C7)alkylene to form a ring; R 6, R 7, R 8 and R 9 each are independently hydrogen, (C1-C50)alkyl, halo(C1-C50)alkyl, (C3-C50)cycloalkyl, (C1-C50)alkoxy, (C6-C30)aryl, (C6-C30)aryl(C1-C50)alkyl, ((C1-C50)alkyl(C6-C30)aryl)(C1-C50)alkyl, (C6-C30)aryloxy, (C1-C50)alkyl(C6-C30)aryloxy, N-carbazolyl, -NR a R b, or -SiR c R d R e, or may be linked to an adjacent substituent via (C1-C5)alkylene to form a ring, and at least one -CH 2 - of the alkylene may be substituted by a hetero atom selected from - 0-, -S-, and -NR'-, and the alkylene may be further substituted with (C1-C50)alkyl; aryl of R 1 to R 12 may be further substituted with at least one substituent selected from the group consisting of (C1-C50)alkyl, halo(C1-C50)alkyl, (C1-C50)alkoxy, (C6-C30)aryloxy, (C6-C30)aryl, (C1-C50)alkyl(C6-C30)aryl, and (C6-C30)aryl(C1-C50)alkyl; R' and R a to R e each are independently (C1-C50)alkyl or (C6-C30)aryl; and X 1 and X 2. each are independently halogen, (C1-C50)alkyl, (C2-C50)alkenyl, (C3-C50)cycloalkyl, (C6-C30)aryl, (C6-C30)aryl(C1-C50)alkyl, ((C1-C50)alkyl(C6-C30)aryl)(C1-C50)alkyl, (C1-C50)alkoxy, (C6-C30)aryloxy, (C1-C50)alkyl(C6-C30)aryloxy, (C1-C50)alkoxy(C6-C30)aryloxy, (C1-C50)alkylidene, or an anion or dianion ligand consisting of 60 or less atoms containing N, P, O, S, Si, and halogen, except hydrogen, provided that one of X 1 and X 2 is a dianion ligand, the other is ignored.