A multinuclear transition metal compound which has two or more catalytic active sites, and is useful in preparing the olefin polymer and copolymer, is disclosed. The multinuclear transition metal compound for olefin polymerization includes two or more metals, and at least one ligand having a cyclopentadienyl moiety, which connects the two or more metals. The preferable multinuclear transition metal catalyst for olefin polymerization includes the first transition metal, the first .eta. ligand having a cyclopentadienyl moiety, which is coordinated to the first transition metal, and the second transition metal to which the second .eta. ligand having a cyclopentadienyl moiety is coordinated, wherein the second transition metal is bonded to the first .eta.-ligand via a sigma (.sigma.) bond.