The present invention provides a catalyst for olefin polymerization having high olefin polymerization activity without being accompanied by generation of an adhered polymer on the wall of a polymerization reactor and the wall of pipe line and generation of a locking massive polymer, and capable of manufacturing an olefin polymer industrially and stably for a long period of time. That is, the present invention related to a catalyst for olefin polymerization comprising [A1] a hafnium compound or a zirconium compound having at least one conjugated 5-membered ring ligand, [A2] a zirconium compound having at least one conjugated 5-membered ring ligand but different from [A1], and [B] phyllosilicate, and relates to a method of polymerizing or copolymerizing olefin in the presence of the catalyst.