A lubricant composition comprising: a viscosity index improver; and a lubricant base oil, wherein the lubricant base oil is a high-purity mineral base oil having a kinematic viscosity at 100°C of 1.4 to 2.5 mm 2 /s and a %CP of the lubricant base oil is 70 or more, the %CP being determined by the method in accordance with ASTM D 3238-85, wherein the viscosity index improver comprises: a copolymer containing, as monomer units, an alkyl (meth)acrylate (a) whose alkyl group contains 5 or more carbon atoms, and an alkyl (meth)acrylate (b) whose alkyl group contains 1 to 4 carbon atoms, wherein the alkyl group of the alkyl (meth)acrylate (a) whose alkyl group contains 5 or more carbon atoms has a molar-average carbon number of 29 or more and 40 or less, and the alkyl (meth)acrylate (a) is at least one selected from the group consisting of 2-tetradecyloctadecyl (meth)acrylate, 2-tetradecylicosyl (meth)acrylate, 2-hexadecyloctadecyl (meth)acrylate, 2-octyldodecyl (meth)acrylate, 2-isooctylisododecyl (meth)acrylate, 2-n-decyltetradecyl (meth)acrylate, 2-isodecylisotetradecyl (meth)acrylate, 2-dodecylhexadecyl (meth)acrylate, 2-tetradecyloctadecyl (meth)acrylate, and an alkyl (meth)acrylate having a C12-C18 linear alkyl group, wherein the molar-average carbon number is calculated by the following mathematical formula Molar − average carbon number Q = ∑ Structural mass ratio of each monomer × Carbon number of alkyl group of each monomer Molecular weight of each monomer ∑ Structural mass ratio of each monomer Molecular weight of each monomer, and wherein the alkyl (meth)acrylate (b) whose alkyl group contains 1 to 4 carbon atoms is contained as a monomer unit in an amount of 38 to 75% by weight based on the weight of the copolymer. a viscosity index improver; and a lubricant base oil, wherein the lubricant base oil is a high-purity mineral base oil having a kinematic viscosity at 100°C of 1.4 to 2.5 mm 2 /s and a %CP of the lubricant base oil is 70 or more, the %CP being determined by the method in accordance with ASTM D 3238-85, wherein the viscosity index improver comprises: a copolymer containing, as monomer units, an alkyl (meth)acrylate (a) whose alkyl group contains 5 or more carbon atoms, and an alkyl (meth)acrylate (b) whose alkyl group contains 1 to 4 carbon atoms, wherein the alkyl group of the alkyl (meth)acrylate (a) whose alkyl group contains 5 or more carbon atoms has a molar-average carbon number of 29 or more and 40 or less, and the alkyl (meth)acrylate (a) is at least one selected from the group consisting of 2-tetradecyloctadecyl (meth)acrylate, 2-tetradecylicosyl (meth)acrylate, 2-hexadecyloctadecyl (meth)acrylate, 2-octyldodecyl (meth)acrylate, 2-isooctylisododecyl (meth)acrylate, 2-n-decyltetradecyl (meth)acrylate, 2-isodecylisotetradecyl (meth)acrylate, 2-dodecylhexadecyl (meth)acrylate, 2-tetradecyloctadecyl (meth)acrylate, and an alkyl (meth)acrylate having a C12-C18 linear alkyl group, wherein the molar-average carbon number is calculated by the following mathematical formula Molar − average carbon number Q = ∑ Structural mass ratio of each monomer × Carbon number of alkyl group of each monomer Molecular weight of each monomer ∑ Structural mass ratio of each monomer Molecular weight of each monomer, and wherein the alkyl (meth)acrylate (b) whose alkyl group contains 1 to 4 carbon atoms is contained as a monomer unit in an amount of 38 to 75% by weight based on the weight of the copolymer. a copolymer containing, as monomer units, an alkyl (meth)acrylate (a) whose alkyl group contains 5 or more carbon atoms, and an alkyl (meth)acrylate (b) whose alkyl group contains 1 to 4 carbon atoms, wherein the alkyl group of the alkyl (meth)acrylate (a) whose alkyl group contains 5 or more carbon atoms has a molar-average carbon number of 29 or more and 40 or less, and the alkyl (meth)acrylate (a) is at least one selected from the group consisting of 2-tetradecyloctadecyl (meth)acrylate, 2-tetradecylicosyl (meth)acrylate, 2-hexadecyloctadecyl (meth)acrylate, 2-octyldodecyl (meth)acrylate, 2-isooctylisododecyl (meth)acrylate, 2-n-decyltetradecyl (meth)acrylate, 2-isodecylisotetradecyl (meth)acrylate, 2-dodecylhexadecyl (meth)acrylate, 2-tetradecyloctadecyl (meth)acrylate, and an alkyl (meth)acrylate having a C12-C18 linear alkyl group, wherein the molar-average carbon number is calculated by the following mathematical formula Molar − average carbon number Q = ∑ Structural mass ratio of each monomer × Carbon number of alkyl group of each monomer Molecular weight of each monomer ∑ Structural mass ratio of each monomer Molecular weight of each monomer, and wherein the alkyl (meth)acrylate (b) whose alkyl group contains 1 to 4 carbon atoms is contained as a monomer unit in an amount of 38 to 75% by weight based on the weight of the copolymer.