A wide-angle optical system including, in order from an object side: a negative first lens that is a glass lens having a convex shape on the object side, a concave shape on an image side, and a spherical surface on either side; a negative second lens that has an aspherical surface on at least one side, and a concave shape on the image side; a positive third lens; an aperture; a fourth lens that has an aspherical surface on at least one side; and a fifth lens that has an aspherical surface on at least one side.