An objective lens for converging a monochromatic light flux having a specific wavelength in a range of 350 to 450 nm on an optical information recording medium while the objective lens is placed facing the optical information recording medium, the objective lens containing a lens body made of a polymer resin having an alicyclic structure; and an antireflection film including one or more layers provided on a surface of the lens body facing to the optical information recording medium, wherein a refractive index of the antireflection film for a light flux having a wavelength of 405 nm is less than 1.7.