A lubricating oil composition comprising a base oil, an alkaline earth metal-based detergent having a base number of from 10 to 500 mgKOH/g as measured according to the perchloric acid method of JIS K-2501, wherein the amount of the alkaline earth metal atom derived from the alkaline earth metal-based detergent is from 10 to 1,500 ppm by mass, 0.01 to 0.5% by mass phosphite ester represented by the following formula: (R 1 O) a P 3-a wherein R 1 represents a hydrocarbon group having 2 to 24 carbon atoms; a represents an integer of 1 to 3; and when a is 2 or 3, R 1, s may be the same as or different from each other, 0.01 to 0.5% by mass phosphate ester amine salt which is an amine salt of an acidic phosphate ester represented by the following formula: (R 4 O) b P(=O) 3-b wherein R 2 represents a hydrocarbon group having 2 to 24 carbon atoms; b represents an integer of 1 or 2; and when b is 2, R 2, s may be the same as or different from each other, 0.01 to 0.8% by mass acidic phosphate ester represented by the following formula: (R 3 O) c P(=O) 3-c wherein R 3 represents a hydrocarbon group having 2 to 24 carbon atoms; c represents an integer of 1 or 2; and when c is 2, R 3, s may be the same as or different from each other, 0.01 to 0.8% by mass aliphatic monoamine represented by the following formula: NR 4 R 5 R 6 wherein R 4 represents an aliphatic hydrocarbon group having 10 to 24 carbon atoms; R 5 and R 6 each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and R 5 and R 6 may be the same as or different from each other, and 0.01 to 1% by mass aromatic monoamine represented by the following formula: NR 7 R 8 R 9 wherein R 7 represents an aromatic hydrocarbon group having 6 to 12 carbon atoms; R 8 and R 9 each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and R 8 and R 9 may be the same as or different from each other; wherein a sum total of the amounts of the phosphorus atom derived from the components to is from 10 to 1,000 ppm by mass, and a sum total of the amounts of the nitrogen atom derived from the components to is from 100 to 3,000 ppm by mass, wherein the % by mass and the ppm by mass are on the basis of the whole amount of the lubricating oil composition. a base oil, an alkaline earth metal-based detergent having a base number of from 10 to 500 mgKOH/g as measured according to the perchloric acid method of JIS K-2501, wherein the amount of the alkaline earth metal atom derived from the alkaline earth metal-based detergent is from 10 to 1,500 ppm by mass, 0.01 to 0.5% by mass phosphite ester represented by the following formula: (R 1 O) a P 3-a wherein R 1 represents a hydrocarbon group having 2 to 24 carbon atoms; a represents an integer of 1 to 3; and when a is 2 or 3, R 1, s may be the same as or different from each other, 0.01 to 0.5% by mass phosphate ester amine salt which is an amine salt of an acidic phosphate ester represented by the following formula: (R 4 O) b P(=O) 3-b wherein R 2 represents a hydrocarbon group having 2 to 24 carbon atoms; b represents an integer of 1 or 2; and when b is 2, R 2, s may be the same as or different from each other, 0.01 to 0.8% by mass acidic phosphate ester represented by the following formula: (R 3 O) c P(=O) 3-c wherein R 3 represents a hydrocarbon group having 2 to 24 carbon atoms; c represents an integer of 1 or 2; and when c is 2, R 3, s may be the same as or different from each other, 0.01 to 0.8% by mass aliphatic monoamine represented by the following formula: NR 4 R 5 R 6 wherein R 4 represents an aliphatic hydrocarbon group having 10 to 24 carbon atoms; R 5 and R 6 each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and R 5 and R 6 may be the same as or different from each other, and 0.01 to 1% by mass aromatic monoamine represented by the following formula: NR 7 R 8 R 9 wherein R 7 represents an aromatic hydrocarbon group having 6 to 12 carbon atoms; R 8 and R 9 each represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; and R 8 and R 9 may be the same as or different from each other; wherein a sum total of the amounts of the phosphorus atom derived from the components to is from 10 to 1,000 ppm by mass, and a sum total of the amounts of the nitrogen atom derived from the components to is from 100 to 3,000 ppm by mass, wherein the % by mass and the ppm by mass are on the basis of the whole amount of the lubricating oil composition.