A catalyst composition for hydrogenation comprising: titanocene dichloride (A); an organometal compound (B) comprising one or two or more elements selected from the group consisting of Li, Na, K, Mg, Zn, Al, and Ca; an unsaturated compound (C); and a polar compound (D) selected from alcohol compounds, ether compounds, thioether compounds, ketone compounds, sulfoxide compounds, carboxylic acid compounds, carboxylate compounds, aldehyde compounds, lactam compounds, lactone compounds, amine compounds, amide compounds, nitrile compounds, epoxy compounds and oxime compounds, wherein a molar ratio of the unsaturated compound (C) to the titanocene dichloride (A) is 0.1 or more and 8.0 or less, a molar ratio of the polar compound (D) to the titanocene dichloride (A) is 0.01 or more and 2.0 or less, and wherein the unsaturated compound (C) is an unsaturated polymer (C1) having a number average molecular weight of more than 400 which has a ratio of an olefinically unsaturated double bond content of a side chain comprised in the unsaturated compound (C1) to a total olefinically unsaturated double bond content of the unsaturated compound (C1) of 0.25 or more and 1.00 or less, or is an unsaturated compound (C2) having a molecular weight of 400 or less, which is a monomer selected from conjugated dienes having 4 to 12 carbon atoms, monoterpene, vinyl aromatic compounds, norbornadiene, cyclopentadiene, cyclohexadiene, 2,3-dihydrodicyclopentadiene and acetylenes, or a polymer prepared by polymerizing one or more of these monomers, or is a combination of the unsaturated polymer (C1) and the unsaturated compound (C2). titanocene dichloride (A); an organometal compound (B) comprising one or two or more elements selected from the group consisting of Li, Na, K, Mg, Zn, Al, and Ca; an unsaturated compound (C); and a polar compound (D) selected from alcohol compounds, ether compounds, thioether compounds, ketone compounds, sulfoxide compounds, carboxylic acid compounds, carboxylate compounds, aldehyde compounds, lactam compounds, lactone compounds, amine compounds, amide compounds, nitrile compounds, epoxy compounds and oxime compounds, wherein a molar ratio of the unsaturated compound (C) to the titanocene dichloride (A) is 0.1 or more and 8.0 or less, a molar ratio of the polar compound (D) to the titanocene dichloride (A) is 0.01 or more and 2.0 or less, and wherein the unsaturated compound (C) is an unsaturated polymer (C1) having a number average molecular weight of more than 400 which has a ratio of an olefinically unsaturated double bond content of a side chain comprised in the unsaturated compound (C1) to a total olefinically unsaturated double bond content of the unsaturated compound (C1) of 0.25 or more and 1.00 or less, or is an unsaturated compound (C2) having a molecular weight of 400 or less, which is a monomer selected from conjugated dienes having 4 to 12 carbon atoms, monoterpene, vinyl aromatic compounds, norbornadiene, cyclopentadiene, cyclohexadiene, 2,3-dihydrodicyclopentadiene and acetylenes, or a polymer prepared by polymerizing one or more of these monomers, or is a combination of the unsaturated polymer (C1) and the unsaturated compound (C2). <EOS>