An imaging lens system includes a first lens group having a positive refractive power and a second lens group having a positive refractive power, the first lens group and the second lens group are sequentially arranged from an object side to an image surface. The first lens group includes a first lens having a positive refractive power, a second lens having a positive refractive power, and a third lens having a negative refractive power and having a concave surface toward the image surface, which are sequentially arranged from the object side to the image surface. The second lens group includes a cemented lens of a fourth lens that has a concave surface toward the object side and is a negative lens and a fifth lens that is a positive lens, which are sequentially arranged from the object to the image surface.