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 comprising: a lens body
containing a polymer resin having an alicyclic structure; a first film
having a refractive index of less than 1.7 for light having a wavelength
of 405 nm; a second film having a refractive index of 1.7 or more for the
light having the wavelength of 405 nm; and a third film having a
refractive index of 1.55 or less for the light having the wavelength of
405 nm, wherein: the first film, the second film and the third film are
provided on the lens body; the first film is provided between the lens
body and the second film; the second film is provided between the first
film and the third film; and a thickness of the first film is in a range
of 50 to 15000 nm.