A photographing lens includes an aperture stop having a predetermined aperture,
a first lens having a positive refractive power and a convex surface facing the
object side, a second lens having a positive refractive power and aspherical surfaces
on both sides, the object-side aspherical surface being concave, and a third lens
having a negative refractive power and aspherical surfaces on both sides, the object
side surface being convex. The aperture stop and the first, second, and third lenses
are arranged in order from the object side toward the image-plane side. With such
a three-unit, three element lens configuration, a proper back focus is ensured,
aberrations are properly corrected, and the total lens length and thickness of
the photographing lens are reduced. The photographing lens can be suitably applied
to high-resolution image pickup devices with a million pixels or more.