An inner focusing telephoto lens system and a photographing apparatus including the inner focusing telephoto lens system includes a relatively larger diameter lens and a lightweight focus lens group. The inner focusing telephoto lens system includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having the positive refractive power. The first lens group, second lens group and the third lens group are arranged sequentially from an object side to an image side. The inner focusing telephoto lens system performs focusing by moving the second lens group along an optical axis.