A syndiotactic styrenic polymer having a narrow molecular weight distribution which is a (co)polymer comprising at least one structural unit represented by the following Formula (1): ##STR1##

wherein C₁ of a phenyl group thereof has a tacticity of 30% or more in terms of a racemic pentad determined by ¹³C-NMR, and R_a and m are as defined in the specification. The disclosure is also directed to a block copolymer comprising the above polymer as one segment, to a block graft polymer prepared by modifying one block of the above polymer with a nitrogen-containing aromatic polymer, and to a process for preparing a syndiotactic styrenic polymer in which a styrenic monomer is polymerized in the presence of a catalyst comprising a reaction product of a transition metal compound and at least one co-catalyst selected from organic aluminunoxy compounds.