To provide a preparing process for a carried, stereorigid metallocene catalyst, especially for a catalyst containing a crystalline silica carrier, which is useful for preparing a stereospecific polymer from an ethylenic type unsaturated compound.

Chains of ethylenic type unsaturated monomers are propagated stereotactically on a carried metallocene catalyst containing a stereospecific metallocene catalyst component and an aluminum-containing catalyst component. The stereospecific metallocene catalyst has two sterically dissimilar cyclopentadienyl groups which are coordinated with a centered transition metal atom. The cyclopentadienyl groups give each other a relation of stereorigidity to the coordinated transition metal atom by means of a bridge or a substituent group, thereby inhibiting the rotation of the ring structures. A silica carrier supporting the catalyst components is a spheroid having an average diameter of 5-40 micron and an average effective pore size of 50-350 angstrom, and it contains at least 50 wt.% of the catalyst components in the pore volume. Above all, a syndiotactic polypropylene may be prepared.