LUBRICATING OIL COMPOSITION

Provided is a lube base oil capable of giving a lubricating oil composition which has a low viscosity, but is small in evaporation amount, has a low coefficient of friction and excellent adaptability for organic materials, and is suitable for use in a high-temperature atmosphere and a lubricating oil composition containing the lube base oil and having such properties. The lube base oil comprises as a main component an ether compound represented by the general formula R 1 -O-R 2 (wherein R 1 and R 2 each independently represents an alkyl group having 2 to 26 carbon atoms) has a kinematic viscosity at 100 °C of 3.5 mm 2 /s or lower, has a mass loss through evaporation as measured through Noack test (at 250 °C; 1 hour) of 30 % by mass or lower and/or has a flash point of 200 °C or higher, and has an aniline point of 60 °C or higher. The lubricating oil composition comprises (A) the lube base oil and (B) an organomolybdenum compound incorporated therein in an amount of 100 to 2,000 ppm by mass in terms of molybdenum amount based on a total amount of the composition.