The polymerization catalyst

Catalyst and preparation method of (A), (B), and (C) is formed: (A) containing titanium, magnesium, a halogen and polycarboxylic acid ester as a main component, and by bringing a magnesium compound, a titanium compound and a polycarboxylic acid the solid titanium catalyst obtained by contacting the ester; (B) an organoaluminum compound; (C) represented by the following formula SiR