A method for manufacturing an ethylene/α-olefin/non-conjugated polyene copolymer, the method comprising copolymerizing an ethylene, an α-olefin having three or more carbon atoms and a non-conjugated polyene in the presence of an olefin polymerization catalyst containing: (a) a transition metal compound represented by the following general formula: wherein Y is selected from a carbon atom, a silicon atom, a germanium atom and a tin atom; M is a titanium atom, a zirconium atom or a hafnium atom; R 1, R 2, R 3 and R 4, each of which may be the same or different, are atoms or substituents selected from hydrogen atoms, C 1 -C 20 hydrocarbon groups, aryl groups, substituted aryl groups, silicon-containing groups, nitrogen-containing groups, oxygen-containing groups, halogen atoms and halogen-containing groups; R 5 and R 6, each of which may be the same or different, are groups selected from aryl groups and substituted aryl groups; adjacent substituents between R 1 and R 6 are optionally bound together to form a ring; Q is selected in an identical or different combination from halogen atoms, C 1 -C 20 hydrocarbon groups, anionic ligands and neutral ligands capable of being coordinated with a lone electron pair; n is an integer of 1 to 4; and j is an integer of 1 to 4; and (b) at least one compound selected from (b-1) organometallic compounds, (b-2) organoaluminum oxy-compounds, and (b-3) components which react with the transition metal compound (a) to form an ion pair. (a) a transition metal compound represented by the following general formula: wherein Y is selected from a carbon atom, a silicon atom, a germanium atom and a tin atom; M is a titanium atom, a zirconium atom or a hafnium atom; R 1, R 2, R 3 and R 4, each of which may be the same or different, are atoms or substituents selected from hydrogen atoms, C 1 -C 20 hydrocarbon groups, aryl groups, substituted aryl groups, silicon-containing groups, nitrogen-containing groups, oxygen-containing groups, halogen atoms and halogen-containing groups; R 5 and R 6, each of which may be the same or different, are groups selected from aryl groups and substituted aryl groups; adjacent substituents between R 1 and R 6 are optionally bound together to form a ring; Q is selected in an identical or different combination from halogen atoms, C 1 -C 20 hydrocarbon groups, anionic ligands and neutral ligands capable of being coordinated with a lone electron pair; n is an integer of 1 to 4; and j is an integer of 1 to 4; and wherein Y is selected from a carbon atom, a silicon atom, a germanium atom and a tin atom; M is a titanium atom, a zirconium atom or a hafnium atom; R 1, R 2, R 3 and R 4, each of which may be the same or different, are atoms or substituents selected from hydrogen atoms, C 1 -C 20 hydrocarbon groups, aryl groups, substituted aryl groups, silicon-containing groups, nitrogen-containing groups, oxygen-containing groups, halogen atoms and halogen-containing groups; R 5 and R 6, each of which may be the same or different, are groups selected from aryl groups and substituted aryl groups; adjacent substituents between R 1 and R 6 are optionally bound together to form a ring; Q is selected in an identical or different combination from halogen atoms, C 1 -C 20 hydrocarbon groups, anionic ligands and neutral ligands capable of being coordinated with a lone electron pair; n is an integer of 1 to 4; and j is an integer of 1 to 4; and adjacent substituents between R 1 and R 6 are optionally bound together to form a ring; Q is selected in an identical or different combination from halogen atoms, C 1 -C 20 hydrocarbon groups, anionic ligands and neutral ligands capable of being coordinated with a lone electron pair; n is an integer of 1 to 4; and j is an integer of 1 to 4; and (b) at least one compound selected from (b-1) organometallic compounds, (b-2) organoaluminum oxy-compounds, and (b-3) components which react with the transition metal compound (a) to form an ion pair. (b-1) organometallic compounds, (b-2) organoaluminum oxy-compounds, and (b-3) components which react with the transition metal compound (a) to form an ion pair.