Specific examples of X include a halogen atom such as fluorine atom, chlorine atom, bromine atom, iodineatom and the like; and an alkyl group having 1 to 20 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, benzyl group and the like.Among the metallocene transition metal compound represented by ML.sub.a X.sub.n-a, specific examples of the compound wher