A catalyst component for olefin polymerization which comprises an intimate mixture of: Component (A1) which is a solid component for Ziegler catalysts comprising titanium, magnesium and a halogen as essential components in a particulate form; and Component (A2) which is a compound selected from the group consisting of inorganic oxides, inorganic carbonates, inorganic sulfates and physical or chemical mixtures thereof in a particulate form; wherein Component (A2) is employed in a weight ratio to Component (A1) from 0.001 to 0.5 and has an average particle diameter smaller than that of Component (A1). The catalyst component may be of a structure such that the particulate inorganic material, Component (A2), adhere to or cover particles of a solid component of a Ziegler catalyst, whereby fluidity of the Ziegler catalyst component is improved.