A wide angle optical system is formed by, in order from the object side, an aperture stop, a first lens with positive refracting power, a second lens with negative refracting power, and a third lens. Both surfaces of the third lens are an aspherical surface in which refracting power varies in accordance with distance from the optical axis in such a way that the both surfaces have a convex shape facing toward the object side in the vicinity of the optical axis and have a concave shape facing toward the object side in the vicinity of the outer circumference, and the following conditions (1) and (2) are satisfied: 0.1