An optical imaging system includes a first lens having negative refractive power, a second lens having negative refractive power, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens. The first to seventh lenses are sequentially disposed from an object side toward an image side. The third lens and the seventh lens are formed of plastic, and the first lens, the second lens, the fourth lens, the fifth lens, and the sixth lens are formed of glass.