Lubricating oil compositions favorably used for food processing machines are disclosed. The oil compositions exhibit highly improved oxidation stability, wear resistance and rust prevention. Raw materials quite harmless to human bodies can be used in the production of said lubricating oil composition which comprises (I) as the base oil, a saturated aliphatic acid glyceride represented by the following general formula wherein R1, R2 and R3 are each a straight-chain alkyl group and (II) as an essential component, an aliphatic acid in an amount of 0.001 to 5% by weight, based on the total composition.