provided is a retrofocus type optical system including a lens or a layer made of a material satisfying the following conditions of the abbe constant νd and partial dispersion ratios θgd and θgf , νd & lt ; 30 , θ gd & lt ;− 3 . 333 × 10 − 3 · νd + 1 . 40 , θ gf & lt ;− 2 . 615 − 10 − 3 · νd + 0 . 67 . in the case that this layer is disposed on the front side of the aperture stop , the layer is designed to have a positive refractive power , and in the case that the layer is disposed on the rear side of the aperture stop , the layer is designed to have a negative refractive index .