A catalyst composition comprising a cis isomer (c) represented by the following Formula 5 and a trans isomer (t) represented by the following Formula 6 of a transition metal compound, wherein the weight ratio of the cis and trans isomers of the transition metal compound is in the range 1-99:99-1: in the above Formulae 5 and 6, M is a group 4 transition metal, Q 1 and Q 2 are the same or different and independently hydrogen; halogen; alkenyl having 2 to 20 carbon atoms; aryl having 6 to 20 carbon atoms; alkylaryl having 6 to 20 carbon atoms; arylalkyl having 7 to 20 carbon atoms; alkyl amido having 1 to 20 carbon atoms; or aryl amido having 6 to 20 carbon atoms, R 1 to R 6 are the same or different and independently hydrogen; silyl; alkyl having 1 to 20 carbon atoms; alkenyl having 2 to 20 carbon atoms; aryl having 6 to 20 carbon atoms; alkylaryl having 7 to 20 carbon atoms; arylalkyl having 7 to 20 carbon atoms; or a metalloid radical of a metal in group 14 substituted with hydrocarbyl having 1 to 20 carbon atoms; R 7 to R 9 are the same or different and independently hydrogen; alkyl having 1 to 20 carbon atoms; alkenyl having 2 to 20 carbon atoms; aryl having 6 to 20 carbon atoms; alkylaryl having 7 to 20 carbon atoms; or arylalkyl having 7 to 20 carbon atoms; n is 0 or 1, R a to R d are the same or different and independently hydrogen; alkyl having 1 to 20 carbon atoms; alkenyl having 2 to 20 carbon atoms; aryl having 6 to 20 carbon atoms; alkylaryl having 7 to 20 carbon atoms; arylalkyl having 7 to 20 carbon atoms, where at least two of adjacent R a to R d are connected to each other to form an aliphatic ring having 5 to 20 carbon atoms or aromatic ring having 6 to 20 carbon atoms, and the aliphatic ring or the aromatic ring may be substituted with halogen, alkyl having 1 to 20 carbon atoms, alkenyl having 2 to 20 carbon atoms, or aryl having 6 to 20 carbon atoms, and R 16 is alkyl having 1 to 20 carbon atoms; alkenyl having 2 to 20 carbon atoms; cycloalkyl having 3 to 20 carbon atoms; aryl having 6 to 20 carbon atoms; alkylaryl having 7 to 20 carbon atoms; arylalkyl having 7 to 20 carbon atoms; or heteroaryl having 2 to 20 carbon atoms. M is a group 4 transition metal, Q 1 and Q 2 are the same or different and independently hydrogen; halogen; alkenyl having 2 to 20 carbon atoms; aryl having 6 to 20 carbon atoms; alkylaryl having 6 to 20 carbon atoms; arylalkyl having 7 to 20 carbon atoms; alkyl amido having 1 to 20 carbon atoms; or aryl amido having 6 to 20 carbon atoms, R 1 to R 6 are the same or different and independently hydrogen; silyl; alkyl having 1 to 20 carbon atoms; alkenyl having 2 to 20 carbon atoms; aryl having 6 to 20 carbon atoms; alkylaryl having 7 to 20 carbon atoms; arylalkyl having 7 to 20 carbon atoms; or a metalloid radical of a metal in group 14 substituted with hydrocarbyl having 1 to 20 carbon atoms; R 7 to R 9 are the same or different and independently hydrogen; alkyl having 1 to 20 carbon atoms; alkenyl having 2 to 20 carbon atoms; aryl having 6 to 20 carbon atoms; alkylaryl having 7 to 20 carbon atoms; or arylalkyl having 7 to 20 carbon atoms; n is 0 or 1, R a to R d are the same or different and independently hydrogen; alkyl having 1 to 20 carbon atoms; alkenyl having 2 to 20 carbon atoms; aryl having 6 to 20 carbon atoms; alkylaryl having 7 to 20 carbon atoms; arylalkyl having 7 to 20 carbon atoms, where at least two of adjacent R a to R d are connected to each other to form an aliphatic ring having 5 to 20 carbon atoms or aromatic ring having 6 to 20 carbon atoms, and the aliphatic ring or the aromatic ring may be substituted with halogen, alkyl having 1 to 20 carbon atoms, alkenyl having 2 to 20 carbon atoms, or aryl having 6 to 20 carbon atoms, and R 16 is alkyl having 1 to 20 carbon atoms; alkenyl having 2 to 20 carbon atoms; cycloalkyl having 3 to 20 carbon atoms; aryl having 6 to 20 carbon atoms; alkylaryl having 7 to 20 carbon atoms; arylalkyl having 7 to 20 carbon atoms; or heteroaryl having 2 to 20 carbon atoms.