Provided is a lubricant composition containing a lubricant base oil and 0.5 to 10 mass % of (A) an ethylene/α-olefin copolymer having a number average molecular weight of 2,800 to 8,000, in which the lubricant base oil used here has a kinematic viscosity at 100° C. of 1.5 to 40 mm2/s, a viscosity index of 100 or more, a pour point of −25° C. or lower, and a sulfur content of 0.01 mass % or less, and the lubricant composition has low viscosity and a long metal fatigue life, while being excellent in low-temperature fluidity and oxidation stability, thereby being particularly suitable as a lubricant for automobile transmissions or the like.