CATALYST COMPOSITION FOR PRODUCING HIGHLY SYNDIOTACTIC POLYSTYRENE AND POLYMERIZATION UTILIZING THE SAME COMPOSITION

PROBLEM TO BE SOLVED: To obtain a catalyst composition having a high catalytic capability, etc., and useful for producing a highly syndiotactic polystyrene, etc., from styrene, etc., at a low cost by containing a titanium (complex), a specific complex and a specific co-catalyst. SOLUTION: This catalyst composition is obtained by containing (A) 0.1-10 mol titanium (complex) not having a cyclopentadienyl ligand expressed by formula I or II (R ' to R ' are each an alkyl, a halogen or the like) with (B) 0.1-10 mol cyclopentadienyl complex of Si, Ge and Sn of formula III (R is H, an alkyl or the like; R , R are each R , or R and R together to form a benzene ring; R , R are each R , or R and R together to form a benzene ring; R is an aryl, H or the like; X is an element belonging to 14th group of the Periodic table such as Si) and (C) an activated transition metal co-catalyst as a mixture of 20-10,000 mol methylalumimnoxane or 0.1-20 mol non-coordinated lewis acid with 100-10,000 mol trialkylaluminum.