Abstract: An object of the present invention is to obtain a lubricating oil for machine tools, which has good lubricating properties and abrasion resistance and also exhibits a high flash point and a low pour point. A lubricating oil composition comprises, as a base oil, a base oil which includes an oil containing 20 mass % to 49 mass % of n-paraffin components and 51 mass % to 80 mass % of i-paraffin components at a quantity of 90 mass % or more of the total quantity of the base oil and which has a kinematic viscosity at 40° C. of 1 to 5 mm2/s. By blending a small quantity of ?-dithiophosphorylated propionic acid and/or an acidic phosphoric acid ester in this base oil, a lubricating oil composition suitable for use for a main shaft of a machine tool is obtained. The lubricating oil composition for a main shaft of a machine tool has a flash point of 100° C. or more, a pour point of ?10° C. or less, and a Shell four-ball wear mark diameter of 0.7 mm or less.