An olefin polymerization catalyst containing a complex of a ligand being a diimine compound represented by the formula (1) and at least one metal selected from the group consisting of Group 8 elements, Group 9 elements and Group 10 elements: wherein Ar1 and Ar2 are respectively a group represented by the formula (2): wherein R1 and R5 are respectively a hydrogen atom or a hydrocarbyl group having 1 to 5 carbon atoms, the total number of carbon atoms of R1 and R5 is 1 or more and 5 or less, and R2, R3 and R4 are respectively a hydrogen atom or an electron-donating group.