A telephoto lens system including a first lens group having a positive refractive power and including a negative lens that is disposed closest to an object side and has a meniscus shape that is convex toward the object side; a second lens group having a negative refractive power and including a single negative lens that moves along an optical axis and performs focusing; and a third lens group having a positive refractive power, wherein the first through third lens groups are disposed sequentially from the object side toward the image side, and the telephoto lens system satisfies the following condition, 0.5