A lubricating oil composition comprising a viscosity index improver together with a base oil, wherein the viscosity index improver comprises a comb-shaped polymer and satisfies the following requirement: Requirement: with respect to a solution having the viscosity index improver dissolved in a mineral oil and having a solid component concentration of 25 mass%, a ratio [(G')/(G")] of a storage modulus (G') to a loss modulus (G") of the solution as measured by the method "Measurement 1" indicated in the description is 0.40 or more, wherein the mineral oil has a kinematic viscosity at 40°C of 17.8 mm 2 /s, a kinematic viscosity at 100°C of 4.07 mm 2 /s, a viscosity index of 131 and a density at 15°C of 0.824 g/cm 3; wherein the comb-shaped polymer is a polymer having at least a constituent unit derived from a macromonomer having a number average molecular weight of 200 or more and a polymerizable functional group, wherein the macromonomer has at least one selected from repeating units represented by the following general formulae (i) to (iii): -(-R 1 -)- (i) -(-R 2 O-)- (ii) wherein, R 1 represents a linear or branched chain alkylene group having a carbon number of 1 to 10; R 2 represents a linear or branched alkylene group having a carbon number of 2 to 4; R 3 represents a hydrogen atom or a methyl group; and R 4 represents a linear or branched chain alkyl group having a carbon number of 1 to 10; wherein a molecular weight distribution (Mw/Mn) of the comb-shaped polymer, wherein Mw represents a weight average molecular weight of the foregoing comb-shaped polymer, and Mn represents a number average molecular weight of the comb-shaped polymer, is 3.00 or less; wherein a weight average molecular weight (Mw) of the comb-shaped polymer is 260,000 to 750,000; and wherein the lubricating oil composition further comprises at least one additive for lubricating oil selected from a pour-point depressant, a metal-based detergent, a dispersant, an anti-wear agent, an extreme pressure agent, an antioxidant, and an antifoaming agent. Requirement: with respect to a solution having the viscosity index improver dissolved in a mineral oil and having a solid component concentration of 25 mass%, a ratio [(G')/(G")] of a storage modulus (G') to a loss modulus (G") of the solution as measured by the method "Measurement 1" indicated in the description is 0.40 or more, wherein the mineral oil has a kinematic viscosity at 40°C of 17.8 mm 2 /s, a kinematic viscosity at 100°C of 4.07 mm 2 /s, a viscosity index of 131 and a density at 15°C of 0.824 g/cm 3; wherein the comb-shaped polymer is a polymer having at least a constituent unit derived from a macromonomer having a number average molecular weight of 200 or more and a polymerizable functional group, wherein the macromonomer has at least one selected from repeating units represented by the following general formulae (i) to (iii): -(-R 1 -)- (i) -(-R 2 O-)- (ii) wherein, R 1 represents a linear or branched chain alkylene group having a carbon number of 1 to 10; R 2 represents a linear or branched alkylene group having a carbon number of 2 to 4; R 3 represents a hydrogen atom or a methyl group; and R 4 represents a linear or branched chain alkyl group having a carbon number of 1 to 10; R 1 represents a linear or branched chain alkylene group having a carbon number of 1 to 10; R 2 represents a linear or branched alkylene group having a carbon number of 2 to 4; R 3 represents a hydrogen atom or a methyl group; and R 4 represents a linear or branched chain alkyl group having a carbon number of 1 to 10; wherein a molecular weight distribution (Mw/Mn) of the comb-shaped polymer, wherein Mw represents a weight average molecular weight of the foregoing comb-shaped polymer, and Mn represents a number average molecular weight of the comb-shaped polymer, is 3.00 or less; wherein a weight average molecular weight (Mw) of the comb-shaped polymer is 260,000 to 750,000; and wherein the lubricating oil composition further comprises at least one additive for lubricating oil selected from a pour-point depressant, a metal-based detergent, a dispersant, an anti-wear agent, an extreme pressure agent, an antioxidant, and an antifoaming agent.