A lubricating oil composition comprising: a mineral lubricating base oil and/or a synthetic lubricating base oil; (a) 200-2000 ppm by mass, in terms of its phosphorus amount in the composition, of a first phosphorus compound represented by formula or formula wherein R 3, R 4 and R 5 independently represent an aryl group having 6 to 30 carbon atoms, an alkyl group having 1 to 30 carbon atoms or an alkenyl group having 2 to 30 carbon atoms; (b) 50-250 ppm by mass, in terms of its phosphorus amount in the composition, of at least one second phosphorus compound selected from a di-2-ethylhexyl acid phosphate amine salt, a dilauryl acid phosphate amine salt, a dioleyl acid phosphate amine salt, a diphenyl acid phosphate amine salt, a dicresyl acid phosphate amine salt, a S-octyl thioethyl acid phosphate amine salt, a S-dodecyl thioethyl acid phosphate amine salt, and an acid phosphite represented by formula wherein R 1 and R 2 each represent hydrogen or a hydrocarbon group having 8 to 30 carbon atoms, at least one of R 1 and R 2 being the hydrocarbon group having 8 to 30 carbon atoms, the hydrocarbon group being an alkyl group, an alkenyl group, an aryl group, an alkylaryl group or an arylalkyl group; and (c) 125-1000 ppm by mass, in terms of its sulfur amount in the composition, of a sulfur compound selected from a thiadiazole compound and a polysulfide compound. a mineral lubricating base oil and/or a synthetic lubricating base oil; (a) 200-2000 ppm by mass, in terms of its phosphorus amount in the composition, of a first phosphorus compound represented by formula or formula wherein R 3, R 4 and R 5 independently represent an aryl group having 6 to 30 carbon atoms, an alkyl group having 1 to 30 carbon atoms or an alkenyl group having 2 to 30 carbon atoms; (b) 50-250 ppm by mass, in terms of its phosphorus amount in the composition, of at least one second phosphorus compound selected from a di-2-ethylhexyl acid phosphate amine salt, a dilauryl acid phosphate amine salt, a dioleyl acid phosphate amine salt, a diphenyl acid phosphate amine salt, a dicresyl acid phosphate amine salt, a S-octyl thioethyl acid phosphate amine salt, a S-dodecyl thioethyl acid phosphate amine salt, and an acid phosphite represented by formula wherein R 1 and R 2 each represent hydrogen or a hydrocarbon group having 8 to 30 carbon atoms, at least one of R 1 and R 2 being the hydrocarbon group having 8 to 30 carbon atoms, the hydrocarbon group being an alkyl group, an alkenyl group, an aryl group, an alkylaryl group or an arylalkyl group; and (c) 125-1000 ppm by mass, in terms of its sulfur amount in the composition, of a sulfur compound selected from a thiadiazole compound and a polysulfide compound. (a) 200-2000 ppm by mass, in terms of its phosphorus amount in the composition, of a first phosphorus compound represented by formula or formula wherein R 3, R 4 and R 5 independently represent an aryl group having 6 to 30 carbon atoms, an alkyl group having 1 to 30 carbon atoms or an alkenyl group having 2 to 30 carbon atoms; (b) 50-250 ppm by mass, in terms of its phosphorus amount in the composition, of at least one second phosphorus compound selected from a di-2-ethylhexyl acid phosphate amine salt, a dilauryl acid phosphate amine salt, a dioleyl acid phosphate amine salt, a diphenyl acid phosphate amine salt, a dicresyl acid phosphate amine salt, a S-octyl thioethyl acid phosphate amine salt, a S-dodecyl thioethyl acid phosphate amine salt, and an acid phosphite represented by formula wherein R 1 and R 2 each represent hydrogen or a hydrocarbon group having 8 to 30 carbon atoms, at least one of R 1 and R 2 being the hydrocarbon group having 8 to 30 carbon atoms, the hydrocarbon group being an alkyl group, an alkenyl group, an aryl group, an alkylaryl group or an arylalkyl group; and (c) 125-1000 ppm by mass, in terms of its sulfur amount in the composition, of a sulfur compound selected from a thiadiazole compound and a polysulfide compound.